On the Life History of Lepoderma ramlianum Looss, 1896, and Its Development from a Xiphidiocercaria

Abstract

During the course of investigations on Bilharzia infections among different snails, I came across a peculiar type of xiphidiocercariae liberated from Bulinus contortus. The cercariae were white in colour with elongated bodies and short stumpy tails. They were extremely sluggish and had a marked tendency to sink towards the bottom of the test tube. Specimens a few hours old, drawn from the tube, were surrounded with a rudimentary cyst wall and the tail was partially attached to them. The body was 0.57 mms. in length by 0.22 mms. in breadth. The tail was 0.3 mms. long in extended specimens. The oral sucker was 8o p in diameter and communicated with a well-developed pharynx leading to a thin oesophagus. This bifurcated, anterior to the ventral sucker into two intestinal ceca reaching as far posteriorly as the border of the body. The ventral sucker was 60 p in diameter. The surface of the body was covered with minute spines attaining their optimum size in the region of the oral sucker where they were arranged in concentric rows; then, they became sparsely distributed over the rest of the surface of the body. Its parenchyma was extremely cellular owing to the presence of numerous cystogenous glands, which obscured the minute details of the excretory system. On either side of the body, there were three stylet glands (fig. 3). Each had a separate duct opening in the vicinity of the stylet. This structure (fig. 4) was thin and fragile. It was partially embedded in the parenchyma of the oral sucker, had no marked shoulders and measured 40 p in length; the spine being onefourth the total length of the stylet. The excretory system (fig. 3) comprised two tubes; the anterior tube received two groups of tributaries, each with a couple of flame cells which drained the regions of the oral and ventral suckers. The posterior tube received a group of tributaries with three flame cells and another with a single flame cell. Both groups drained the region posterior to the ventral sucker. The two tubes joined each other at the level of the posterior margin of the ventral sucker, forming a thick main tube. The main tube from either side opened directly into the excretory vesicle, which received the main tributary from the tail, at its posterior margin. The formula of the excretory system would be 2 X (2 + 2) + (3 + I) I6. The cercariae developed in rediae (fig. i) about i mm. in length