ventral and dorsal borders. Eighth sternite with three bristles on each side, the middle one of each being greatly the longest.

Length 1 mm.

Described from a single male specimen, the holotype, taken from a white-footed mouse captured in Lolo Canyon, at the mouth of Bear Creek, three miles west of Woodman, Mont., May 6, 1922. The slide bears the record number 468-6, and is in the collection of the senior author.

CTENOPSYLLUS RAVALLIENSIS, new species.

FEMALE.

Head.-Occiput nearly flat dorsally. Frons strongly rounded to the vestigial frontal notch, the lower portion sloping backwards. The antennal groove extends to upper margin of the head. Eye absent, being merely represented by a small, round, thickening of the chitin. Two heavy etenidial spines are inserted at the posterior border of the gena, below the eye spot. Either side of the frons has a marginal row of 7 bristles and 4 short black spines, the latter occurring near the frontal notch, with 2 of the bristles above them and the other 5 below on the sloping lower portion of the frons. Lower genal row with 2 bristles, upper row with 2, and a single bristle placed above the upper row. Seventeen short bristles and 1 long one on each side of the occiput anterior to the hind marginal row, the long bristle arising near the hind margin of 'antennal groove and extending beyond the apex of the occiput. Hind margin of occiput with 8 bristles on each side, a short, heavy, black one being at each lower posterior angle. The mouth parts extend to slightly beyond the middle of the anterior coxa.

Thorax.-Pronotum with etenidium of 24 spines and an anterior row of about 10 long bristles. The mesonotum bears a posterior row of 10 bristles, 2 irregularly curved rows of 14 bristles each, 2 shorter curved rows of about 10 each, and a transverse row of about 16 very small bristles anteriorly. The metanotum with from 8 to 10 large bristles in a posterior row and about 20 smaller ones irregularly placed anteriorly. Mesosternite with 6 bristles on episternum. 5 being in a row and 1 placed singly, 7 irregularly arranged bristles on the epimerum and 2 large and 1 small one on the stigmal plate. Metasternite with 2 bristles, 1 large and 1 small, on the episternum and 1 long, heavy one on the sternum. There seems to be considerable variation in the number and arrangement of bristles on the pleural plates of specimens of this species.

Abdomen. Each tergite with two rows of bristles, anterior row on each tergite except the seventh containing about 10 small bristles, the seventh bearing only 2; the posterior rows on the second, third,

and fourth tergite contain 14 large bristles, the fifth and sixth each have 10, and the seventh has about 12. Small teeth on either side of dorsal margin as follows: One on metanotum, 2 on first tergite, 2 on second, 2 on third, 1 on fourth, and 1 on fifth. The middle abdominal sternites each with a row of 8 bristles.

Legs.---Hind coxa with a few bristles on outer lateral surface near the anterior margin apically. Hind femur with a posterior marginal row of about 14 small bristles, a subapical row of 4 large bristles and 2 curved spines, 1 long and 1 short, at apex. Hind tibia with 4 long spines, 2 being set together near the base and 13 short ones on the posterior margin: a row of 9 bristles on the outer lateral margin. Spines on tarsal segments short. The first pair of spines on fifth segment located near the median line, almost between the second pair.

Modified segments. Four antepygidial bristles on each side, the inner one being less than half the length of the outer three. The number of antepygidial bristles varies in this species, some examples apparently having 4 on each side, others having 4 on one side and 3 on the other and still others having 3 on each side. Numerous small bristles on eighth tergite. A small mass of bristles on tenth tergite. Style short and stout, being less than twice as long as wide, with 1 subapical and 4 apical bristles. Substylar flap small with several stout bristles at apex and lower margin. One long bristle located well below the pygidium.

MALE.

Modified segments. Three antepygidial bristles on either side, the middle one of each set being more than twice the length of either of the outer ones. Two bristles on the lower lateral border of the ninth tergite just below the pygidum. Tenth tergite with about 6 short bristles at apex. Manubrium of medium length, slightly curved upward and pointed at tip. Upper part of process extending posteriorly. Exopodite relatively small, roughly triangular in shape, does not quite reach upper margin of process and has 3 bristles and several small hairs on the posterior border. Ninth sternite curved ventrally and bearing a row of small bristles. Eighth sternite with heavy bristles near apex.

Eleven specimens of this flea were found on two pack rats taken at the southern end of Ravalli County, for which county the flea was named.

Holotype: Male: from a pack rat taken on Tin Cup Creek, in the foothills of the Bitterroot Mountains southwest of Darby. Mont., August 31, 1922. The slide bears the record number 199-6.

Allotype: Female: from a pack rat taken on Spoon Creek in the foothills of the Bitterroot Mountains southwest of Darby. Mont., August 16, 1922. The slide bears the record number 161 -6.

The above type specimens are deposited in the collection of the United States Public Health Service at the Hygienic Laboratory, Washington, D. C.

CATALLAGIA CHARLOTTENSIS Baker.

Four specimens of this flea were collected, one on a snowshoe rabbit, one on a chipmunk, and two on a forest white-footed mouse.

HYSTRICHOPSYLLA DIPPIEI Rothschild.

Specimens of this large flea were found on a chipmunk and a pine squirrel.

NEOPSYLLA INOPINA Rothschild.

This species was taken on ground squirrels, on a woodchuck, and on a snowshoe rabbit.

NEOPSYLLA WENMANNI Rothschild.

Seven specimens of this flea were collected from a white-footed mouse; also two from two pine squirrels.

NEOPSYLLA HAMILTONI, new species.

FEMALE.

Frontal notch small.

Head.-Rounded anteriorly. Frontal notch small.

Rostrum half the length of fore coxa. Eye absent. Gena with 5 long etenidial spines, the middle 3 longest. Upper genal row of 5 bristles; lower row with 2 long ones, 1 placed on anterior margin of antennal groove and the other midway between the groove and the maxillæ. Occiput with 6 bristles, arranged in two oblique rows, on either side, and a marginal row of 10 bristles.

Thorax. Pronotum with a ctenidium of 22 spines and a row of 10 bristles. Mesonotum with one row of 8 medium-sized bristles and two rows of very small ones. Metanotum with one row of 8 large bristles and a second one of 10 smaller ones. Mesosternite with 5 bristles. Metasternite with 1 bristle on episternum and 1 on

sternum.

Abdomen.-Tergites each with a row of 12 large bristles and a second row of 8 or 10 smaller ones. First and second tergites each bears 3 small, black teeth on either side, the third has 2 and the fourth 1. Each of the sternites bears a single row of 6 or 8 bristles. Legs.-Fore tibia with spine reaching to middle of third tarsal segment. Mid tibia with spine reaching to middle of second segHind coxa with small teeth on inside. Hind femur with a row of small bristles on posterior margin and two on anterior margin near apex. Hind tibia with five pairs of spines and one single one, the latter proximally. Longest tibial spine about three-fourths as long as the first tarsal segment. First segment of hind legs with a spine

ment.

as long as the second segment, the latter with a spine reaching nearly to the middle of the fourth segment. Fifth segment on mid and hind legs with four pairs of lateral spines and a pair of lateral apical bristles.

Modified segments.-Two antepygidial bristles of equal length on either side. Tenth tergite long posteriorly and bearing several bristles. Style long and slender with two apical bristles, one long and the other short. Substylar flap with deep notch on lower margin at base and bearing a basal group of small bristles and several longer ones near the apex. A group of stout bristles on the eighth segment below.

Described from one female specimen, the holotype, taken from a pack rat captured on Spoon Creek, southwest of Darby, Mont., August 16, 1922. The slide bears the record number 161-7, and is in the collection of the senior author.

CERATOPHYLLUS ACAMANTIS Rothschild.

The woodchuck is the favorite host of this flea, practically all of which animals that were secured being found heavily infested with this species. Although the infestations are heavy during all months that the woodchucks are active, these fleas are present in greater numbers during March and April, when the animals emerge from their dens after hibernating. At this time between 200 and 300 specimens may be found on many of the animals. This would indicate that the fleas greatly multiply in the dens during the winter months. This species is quite active and will bite man, the writer having received several bites from this species while collecting them from the animals.

CERATOPHYLLUS ACASTI Rothschild.

This species is found on the flying squirrel, being fairly numerous on these densely furred animals during all seasons of the year.

CERATOPHYLLUS AGILIS Rothschild.

This species was found to be quite common on pack rats taken in various areas throughout the valley. A few specimens were also collected from several other varieties of animals.

CERATOPHYLLUS BITTERROOTENSIS, new species.

Head.--Flattened above; well rounded in front. Frontal notch very small. Three good sized bristles in lower genal row and two small ones in the upper row, one of these latter being close to the antennal groove and the other on lower margin of head. A number of small hairs along front margin of antennal groove. Eye small, roundly pointed below and well pigmented. Gena acute posteriorly. One medium sized bristle located back of the antennal groove. A

number of slender bristles on hind margin of head and a large one at each lower angle. Antennal groove reaching to upper margin of head. Rostrum extending to about one-third of the fore femora.

Thorax. Pronotum with a etenidium of 20 spines and a row of 10 small bristles. Mesonotum and metanotum each with a row of from 6 to 8 small, light-colored bristles and a posterior row of S or 10 larger ones. Stigmal plate of mesosternite with 2 long bristles.

Abdomen. Abdominal tergites each bears one row of about 12 bristles with a small hair between each 2 and a second row of from 4 to 8 small bristles. Sternites each with a row of from 4 to 8 bristles.

Legs. Hind coxa with row of small bristles along anterior border. about 10 more on lateral surface, and 2 longer ones at the lower part of the notch in posterior margin. Hind femur with about 11 small bristles on the posterior margin with 1 large curved one at the apex: a single row of 7 bristles on the lateral surface and 2 longer ones on the anterior margin. 1 at the base and the other near the apex. Hind tibia with 5 pairs of spines and 3 single ones on posterior margin and 2 pairs on anterior apical margin. Longest spine at apex of tibia reaches about three-fourths of first tarsal segment. None of the hind tarsal spines appreciably longer than the following segment. Mid tibia with an apical spine longer than first and second segments combined.

Pygid

Modified segments. One antepygidia! bristle on each side. ium small and blunty cone shaped. Tenth tergite with 3 long bristles at apex. Subapical flap with 2 bristles at tip. Manubrium short, pointed, and extending downward. Process with a rounded tip extending posteriorly on upper portion; slightly concave on lateral posterior margin with 2 slender bristles arising from the concavity. Exopodite reaches to level of process; flat on anterior border above the pedicle and convex on posterior border with 3 pointed black spines at margin and 1 bristle and some small hairs above. The ninth sternite bears 2 long bristles and several small hairs. Eight. sternite long and slender with 4 long bristles on the ventral surface near the tip.

Described from two male specimens.

Holotype: Male; from a pack rat captured on Spoon Creek soutir west of Darby, Mont.. August 16, 1922. The slide bears the record number 161--1, and is held by the senior author.

CERATOPHYLLUS CILIATUS Baker.

Eight specimens of this flea were collected from 5 chipmunk and I pine squirrel. The largest number found on an animal was 2.

CERATOPHYLLUS DIVISUS Baker.

Four specimens of this species were found on 4 pine squirrels.