Comparative studies on certain species of Diphyllobothrium .

In a previous paper (Mueller, I935), the writer described as new a species of Diphyllobothrium from cats in the Syracuse area, under the name D. mansonoides. At that time, and since, doubt has been entertained in some quarters as to the validity of this species. Skinker (I935) states: "In the description of Diphyllobothrium mansonoides Mueller, I935, no morphological details are given which the present writer accepts as constituting adequate characters for specific differentiation of this species from D. mansoni (Cobbold, I882) Faust and Wassell, I92I. D. mansonoides is, therefore, considered a synonym of D. mansoni." At the time of the original description, comparisons with D. mansoni were made on the basis of the published descriptions of that form. Since then, however, material of this species has been secured for comparative morphological study, the results of which are herewith presented. The material used consisted of 19 specimens of D. mansonoides collected from Syracuse cats since I933. No further data have been secured on the possible occurrence of this worm in dogs. To date, 212 cats have been examined, of which 10 were found infected with the worm, making an incidence of 4.6 per cent. These cats were examined during the months from February to June, inclusive, of different years, and of the 10 infested cats, 5 were found during the month of March. Unfortunately, our examinations were not sufficiently distributed to indicate whether there is a seasonal variation in incidence or not. Six of the 10 cats harbored a single worm; one had 2 worms, another 3, and the remaining two cats 4 each. I am greatly indebted to two of my former students, Mr. Carlton Herman and Mr. Robert Perry, who examined many cats for me, and who assisted in other ways in the study of this parasite. Material of all of the mansonoides taken to date has been studied in detail to determine the limits of variation. Whole mounts were made of pieces from each strobila. Nineteen sets of serial sections were prepared. The general measurements of the species, as given previously, must be emended. The maximum length, formerly given as 60 cm., must be raised to I40 cm. (55 inches); the maximum width from 7 mm. to IO mm. On April I6, I936, a large pregnant female cat was found to harbor three unusually large worms, the biggest of which had the dimensions indicated. The other two worms were respectively 89 cm. (35 inches)