Page:Transactions of the Royal Society of Tropical Medicine and Hygiene, volume 1.djvu/102

78 there are in each species ten pairs, four pedunculated and six sessile. The pedunculated series lies in a longitudinal row, outside the sessile papillae. Though the number appears to be constant for most, at any rate, of the species, the relative position of the papillae to one another seems to be of specific value.

The vulva is situated in the anterior half of the body, and the ova show an exceedingly thick smooth shell, that in itself is highly characteristic.

The species obtained in Uganda and which we shall call P. mordens, like P. cawcasica presents all the characters above defined, as those of the genus in a restricted sense. Its size is very considerable, the male measuring 30 to 50 mm., the female 40 to 55 mm. In shape and general appearance it resembles an immature Ascaris lumbricoides—so much so as to lead me to conclude that it may have been frequently overlooked as such in the past, just as Ascaris mystax and Ascaris marginata have been. To the latter, also, it" bears a striking resemblance, the bursal expansion at the tail of the male resembling the cuticular alae that are present at the head of these two species.

The breadth of the worm is considerable, and varies from two to three millimetres. The body tapers very gradually anteriorly, and ends truncately; posteriorly it tapers rapidly in the female to a sharp tip, lying more in line with the ventral than the dorsal surface, and giving therefore the posterior portion of the worm a somewhat rounded appearance on the whole. In neither sex does the cuticle form posteriorly a preputial fold around the posterior portion of the body, as it does in some species in addition to the characteristic anterior bulging seen in all. The cuticle shows adventitious groovings that have no constant relation to one another. In this species, however, it is not absolutely without structure, exceedingly fine radiate striae being noticeable.