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CERATOPHYLLUS EUMOLPI Rothschild.

This species is commonly found on the yellow-bellied chipmunks, these small animals undoubtedly being the favorite hosts. A few specimens were also taken on pine and ground squirrels.

CERATOPHYLLUS IDAHOENSIS Baker.

Fleas of this species were found infesting a large percentage of the many ground squirrels examined. They appear to be more numerous in the early spring when the squirrels emerge from their winter hibernation than during the midsummer months, although they are commonly found throughout the season. It was with some hesitation that the writer first classified these fleas as idahoensis. This was owing to the minor differences present between them and the description of this species as given by Baker. However, after examining a series of 377 specimens and carefully studying the variation that occurred, it is believed that they may be safely placed in this species. This variation in minor characters seems to be more marked among specimens of this flea than in any of the other species examined during these observations with the possible exception of S. inequalis. This consisted of differences in the spines of the eighth segment, subpygidial spines, teeth or tergites, pronotal spines, bristles in genal rows, prominence of tubercle of frons, and in various other characters.

CERATOPHYLLUS LUCIDUS Baker.

This species was found on many pine squirrels and apparently becomes more numerous during the late summer months.

CERATOPHYLLUS POEANTIS Rothschild.

Ten specimens of this flea were collected from 3 side-striped ground squirrels.

CERATOPHYLLUS TELCHINUM Rothschild.

This species was taken on forest white-footed mice, mountain meadow mice, and a cottontail rabbit. Only 1 specimen was present on each animal with the exception of 1 white-footed mouse, which was found to be host for 8 of these fleas.

CERATOPHYLLUS TUBERCULATUS Baker.

Common on ground squirrels together with C. idahoensis, but usually not as numerous as the latter species. Minor differences of characters are frequently found occurring in specimens of this flea.

CERATOPHYLLUS WAGNERI Baker.

A large percentage of the forest white-footed mice that were examined were found to be harboring this species. Five was the largest number taken from one mouse.

CERATOPHYLLUS WICKILAMI Baker.

Practically all the pine squirrels secured were infested with this species, and these animals are apparently the favorite hosts. The largest number taken from one squirrel was 21. Twelve specimens of this flea were also collected from a mountain weasel, and 2 from a yellow-haired porcupine.

ANOMIOPSYLLUS XUDATUS Baker.

Eight specimens of this small flea were found on a western horned owl. Although taken from an avian host, this species is included in this list of fleas from mammals, owing to the fact that in all previ ous records of the occurrence of nudatus, small rodents have been the hosts. As the horned owl is predaceous in habits, and as its food consists largely of small rodents, it is a question whether this bird may be considered a normal host of this species of flea or merely a temporary one that had become infested from the small rodents on which it had preyed.

Further work on the fleas which infest the wild animals in this valley will undoubtedly disclose additional new species as well as other species previously described that are not included in the foregoing list.

Specimens of the new species described in this paper were sent to Surg. Carroll Fox, United States Public Health Service, at Washington, D. C., who compared them with the literature and with specimens in the National Museum and in his own collection.

Acknowledgments.Thanks and appreciation are extended to Surg. R. R. Spencer, officer in charge of this station, for the interest that he has shown in this work and also for his assistance in collecting many of the fleas; and to Surg. Carroll Fox.

Host Index.

The following host index illustrates the species and comparative prevalence of the fleas found on the various wild animals in the Bitterroot valley. The numbers following the names denote the number of fleas or animals of the variety indicated; e. g., "cottontail rabbits, Sylvilagus nuttalli, 31," signifies that 31 cottontail rabbits were found infested with fleas of various species: and "Spilopsyllus inequalis, 721," indicates that 724 fleas of the species S. inequalis were collected from the 31 cottontail rabbits, etc.

Cottontail rabbits, Sylvilagus nuttalli, 31: | Side-striped ground squirrels, Callosper

Spilopsyllus inequalis, 724.

Odontopsyllus spenceri, 12.

Ceratophyllus idahoensis, 5.

Ceratophyllus wagneri, 3. Ceratophyllus acamantis, 2. Ceratophyllus agilis, 2. Ceratophyllus telchinum, 1. Hoplopsyllus affinis, 1. Snowshoe rabbits, Lepus bairdi, 23: Spilopsyllus inequalis, 68. Hoplopsyllus affinis, 23. Odontopsyllus spenceri, 9. Ceratophyllus agilis, 2. Ceratophyllus idahoensis, 2. Ceratophyllus charlottensis, 1. Ceratophyllus wagneri, 1. Neopsylla inopina, 1.

Jackrabbits, Lepus campestris, 2:

Spilopsyllus inequalis, 8.

Ground squirrels, Citellus columbianus, 94:

Ceratophyllus idahoensis, 363.
Ceratophyllus tuberculatus, 91.
Neopsylla inopina, 15.
Ceratophyllus eumolpi, 9.

Ceratophyllus poeantis, 4.

Spilopsyllus inequalis, 3.

Ceratophyllus lucidus, 1.

Pine squirrels, Sciurus hudsonicus richard

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mophilus lateralis cinerascens, 3:

Ceratophyllus poeantis, 10.

Yellow-bellied chipmunks, Eutamias lu

teiventris, 44:

Ceratophyllus eumolpi, 82.

Ceratophyllus ciliatus, 7.

Hystrichopsylla dippiei, 4.

Calallagia charlottensis, 1.
Ceratophyllus wickhami, 1.

Woodchucks, Marmota flaviventer, 19:

Ceratophyllus acamantis, 294.

Ceratophyllus idahoensis, 4.
Ceratophyllus tuberculatus, 1.
Neopsylla inopina, 1.

Forest white footed mice, Peromyscus

maniculatus artemisiae, 13:
Ceratophyllus wagneri, 19.
Ceratophyllus telchinum, 10.
Neopsylla wenmanni, 7.
Catallagia charlottensis, 2.

Micropsylla peromyscus, 1.

Rocky Mountain meadow mouse, tus mordax mordar, 1:

Ceratophyllus telchinum, 1. Pack rats, Neotoma cinerea, 6: Ceratophyllus agilis, 43. Clenopsylius ravalliensis, 11. Ceratophyllus bitterrootensis, 2. Ceratophyllus idahoensis, 2. Neopsylla hamiltoni, 1.

Pika, Ochotona princeps, 1:

Ceratophyllus agilis, 4.

Micro

Arizona weasel, Putorius arizonensis, 1:

Ceratophyllus wickhami, 12.
Ceratophyllus acasti, 1.

Yellow-haired porcupine, Erethizon epiranthium, 1:

Ceratophyllus wickhami, 2.

Northern coyotes, Canis latrans, 4:

Spilopsyllus inequalis, 11.

Ceratophyllus acamantis, 1.

Ceratophyllus lucidus, 1.

Western horned owl, Bubo virginianus occidentalis, 1:

Anomiopsyllus nudatus, 8.

AN EPIDEMIOLOGICAL STUDY OF WHOOPING COUGH IN AMSTERDAM.

In the Medical Officer for October 20, 1923,1 Dr. B. H. Sajet and J. V. Gelderen, statistician, present the results of their epidemiological study of the occurrence of whooping cough in Amsterdam over a period of several years.

In view of the incompleteness of statistical analyses of various epidemiological factors in whooping cough, the study made by the investigators, although based on a comparatively small strength, is a contribution to the knowledge of this disease. The authors show the variation of the attack rate and death rate with respect to age, social condition, size of family, and nationality.

Use was made of the vital statistics records of the city, and additional information was obtained by means of an inquiry among school children, enabling the investigators to examine 13,500 cards which, at the request of the statistical office, had been filled in by parents of the pupils attending the highest and the lowest classes of the primary schools. This information proved unsatisfactory, however, as data upon which to base an estimate of the actual prevalence of the disease. According to the entries made by the parents on the cards, 36.1 per cent of 7,111 boys and 42.3 per cent of 6,479 girls had had whooping cough. It is inferred that many parents either did not remember, in some instances, that one or another of their children had suffered an attack, or had not recognized it, and that this occurred oftener among the poorer classes, among whom the lowest incidence was found, as compared with an attack rate of 55 per cent among the well-to-do. It was stated that the average probably lies nearer 65 per cent.

Age and mortality. The deaths from whooping cough per 100 deaths in children under 14 years of age from all causes in Amsterdam and the whole of Holland are given as follows:

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Of a total of 487 deaths from whooping cough in Amsterdam in the period 1908 1911, the mortality by age groups was as follows:

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From an examination of the school medical records, in which the history of children who had had whooping cough at pre-school age was also noted, the following data were found:

The Coatrol and Prevention of Whooping Cough. By B. H. Sajet, M. D., and J. V. Gelderen statis

tician.

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PER CENT ATTACKED IN EACH AGE GROUP OF TOTAL NUMBER ATTACKED.

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From these tables it is seen that nearly 90 per cent of the boys affected and 86 per cent of the girls had contracted the disease before reaching the age of 6 years, emphasizing the statement of Pfaundler that "The age of onset should be retarded."

Sex and mortality.—A comparison of the death rates from whooping cough for Amsterdam and for the whole of Holland shows, characteristically for the disease, a higher rate among girls than among boys, the ratio of the rate among girls to that among boys during the period 1908-1911 being 100 to 88 in Amsterdam and 100 to 85.6 in the whole of Holland. It is stated not to have been determined definitely whether the higher death rate among girls represents a greater liability to attack or a higher case fatality rate, representing greater virulence of the disease in girls; although the information at hand indicated a higher attack rate as being the more important factor.

The rates of the history of present or previous attacks in boys as compared with girls was 85.1 to 100.

Influence of age and social condition upon incidence and mortality.— The following tables are presented to show the influence that social status appears to exert upon the incidence of and mortality from the disease at various age groups of school children.

Percentage of attacks in children of families from which children attended ordinary primary schools, advanced schools first class, or advanced schools second class.

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