30 



" TERRA NOVA" EXPEDITION. 



terminal position of the anus, the posterior situation of the vulva, and the production of 

 thick-shelled eggs, necessitate the separation of this form from the genus Filaria in its 

 modern acceptation. We regard the present species as the type of a distinct genus, for 

 which we have proposed the name Crassicauda, 



ACANTHOCEPHALA. 



Corynosoma, Liihe. 



8. Corynosoma hamanni (v. Linst.). (PI. II, figs. 11, 12.) 



Echinorhynchus hamanni, v. Linstow. 

 Corynosoma antarcticum, Rennie. 

 EcMnorhynchus antarcticus, Rennie. 



,, sipho, Railliet and Henry. 



Hosts. — These thorn-headed worms were found in considerable numbers in 

 Weddell's Seal, the Crab-eating Seal, and the Sea-Leopard, attached firmly to the 

 mucous membrane of the small intestine. 



Parasite. — The parasites are pyriform and might in haste be mistaken for Amphi- 

 stomes. The rostellum (PI. II, fig. 11, a) is partially sunken into the broader and 

 globular end, thus producing some resemblance to the ventral sucker of many of the 

 Paramphistomidae. The species was also found by the Scottish Antarctic Expedition, 

 and has recently been the subject of a monograph by Dr. John Rennie. With his 

 account our findings tally, save in three respects. 



(a) The number of hooks upon the rostellum is, according to our reckoning, 150 

 to 170, whereas Rennie states that there are about 28 rows, each having ten 

 hooks. 



A re-examination of the type-material of E. antarcticus shows that this discrepancy 

 is probably attributable to a different mode of counting. Owing to their peculiar 

 alternating arrangement, the hooks may be counted in a spiral fashion as well as in 

 vertical rows. 



(A) We have not found any departure from the normal arrangement in the male 

 genital system. 



As this has not been previously portrayed, it is illustrated in Fig. I I. 

 (r) In dealing with its systematic position, Rennie contrasts this form with allied 

 forms parasitic in aquatic birds. 



The species which Dr. Rennie regarded as new would appear to be even more 

 closely related to Echinorhynchus semerme Forskal from Phoca vititlina, and to be 

 synonymous possibly with E. hamanni v. Linstow from Weddell's Seal. In all three 

 forms the spines on the body extend along the whole of the ventral aspect and envelop 

 the posterior extremity (PI. II, fig. 11. //). The number of longitudinal rows of hooks 

 in E. semerme is stated to be twenty-four to twenty-six ; v. Linstow gives for 



