1903.] ENTO-PARASITES OP THE " SKEAT EXPEDITION." 147 



sion. The number of calcareous bodies is small, and other deeply 

 staining structm-es, e.g. the nuclei and muscle-fibres, are but sparsely 

 scattered through the tissues. There is a four-cornered nerve- 

 mass well lying about the level of the juncture of the anteiioi- one- 

 third with the posterior two-thirds of the bothria, and this gives 

 ofi' four strands which pass peripherally and probably supply the 

 bothria and introverts. I did not see any longitudinal nerves, 

 though probably they exist. 



In his exhaustive monograph * " Recherches sur les Tetra- 

 rhynques," VauUegeard records his opinion that the numerous 

 species of Tetrarhynchous Cestodes belong to but one genus, Tetra- 

 rhynchus. Raillet has pointed out that the generic name 

 RhyncohothriibS Rudolphi, 1819, has precedence of Tetrarhynchios 

 1809, the latter name having been given to a lai-val form. In the 

 present case, although it may be inconsistent with the laws of 

 nomenclature, I have followed VauUegeard, partly because every- 

 one knows what Tetrarhynchus is, and partly because, in my 

 opinion, needless confusion is introduced into the study of tape- 

 worms by using a double nomenclature for larvae and adults. In 

 civilized society it is not considered necessary for a human being 

 to change his name when he leaves the home of his childhood and 

 sets up in a new house, and there seems as little reason for a 

 young Oestode to change its name when it changes its host. 



VauUegeard arranges the various species into two sections, one 

 of which, on the type of T. lingtmlis Ouv., has in its larval form 

 no vesicle projecting over and protecting the head. To this 

 section the cestode in qtiestion belongs. The larvfe which were 

 collected by the Skeat Expedition were some of them wholly and 

 some of them partly enclosed in cysts, but none of them showed 

 any trace of the projecting vesicle. 



Tetra/rhynchus holothurice, n. sp. (Plate XVI. figs. 5, 6, & 7.) 



The larval form (but not the encysted form) is 6 mm. long by 

 1 mm. broad. Tapering posteriorly where there is a depression 

 receiving the excretory pore. The two large bothria are sub- 

 divided by a ridge. The four introverts are provided with a cap 

 of hooks pointing forward at the tip and a circular band of hooks 

 pointing backward, between these two toothed regions is a con- 

 sidei'able portion devoid of hooks. 



Habitat. A common Holothurian, probably a Molpadia, taken 

 oflF the mouth of the Patani River. 



Tetrabhynchus sp. (Plate XVI, figs. 8 & 11.) 



Some eight or nine small cysts about the size of very poor wheat- 

 seeds were taken from the body of a sea-snake, Enhydrina vala- 

 kadien Boie. Unfortunately the position of the cysts in the body is 



* M«m. Soc. Normandie, xix. 1897-1899, p. 185. 



10* 



