1910.] ENTOZOA OF THE HIPPOPOTAMUS. 237 



In the female the anus opens 0*95 mm. from the posterior 

 extremity. The vulva is 0*07 mm. in front of the anus. The 

 anatomy of the female organs cannot be accurately determined as 

 these structures are greatly distended by two or three embryos of 

 enormous size, the containing cyst measuring 03 mm. by - l mm. 

 This retention of the ovum within the maternal body until it has 

 completed its larval development and has attained adult form, is 

 found also in Probstmayria vivipara which occurs in horses in 

 various parts of the world. 



I have named this genus in honour of the late Dr. Cobbold. 



CESTODA. 



No tapeworms were present in any of the animals examined. 

 Cobbold mentions that " Livingstone has drawn attention to the 

 fact that the river-horse is much infested by tapeworms," but I 

 cannot find a description of such parasites anywhere in literature. 



TREMATODA. 

 Family Fasciolid.e. 

 Genus Fasciola. 

 4. Fasciola nyanz^e, sp. n. (Text-fig. 28, p. 238.) 



This species was found exclusively in the bile-ducts of the liver, 

 and in most instances the specimens were somewhat macerated 

 owing to the length of time that necessarily elapsed before the 

 animal could be recovered from the water. 



The genus Fasciola, in the restricted sense in which it was used 

 first by Cobbold, comprises only the species F. hepatica, F. gigan- 

 tica, F. magna, from Ruminants, and F. jacksoni from Elephants. 

 These four species differ mainly in the shape and size of the body, 

 the character of the internal branches of the gut and the dis- 

 tribution of the yolk- glands, especially with reference to their 

 encroachment upon that region of the body which lies between 

 the main gut branches. F. nyanzce is more closely related to 

 F. hepatica and F. gigantica than to the other forms, differing 

 mainly in the feeble development of spines on the integument, 

 and the restriction of the branched testes to the anterior third 

 of the borly. 



Form, etc. — The parasite measures 69 mm. in length ; greatest 

 breadth 9 # 3 mm., i. e. in the proportion of 7 to 1, whereas in 

 F. hepatica the proportion is only 2 to 1, and in F. gigantica 

 4 to 1. 



The cephalic cone is well defined and when contracted measures 

 3 mm. in length. 



The body expands almost immediately behind the cone to attain 

 its greatest diameter, whence it tapers very uniformly to the 

 posterior end of the body, having midway a diameter of only 

 6 mm,, and 3 mm. at less than 2 mm. from the posterior end. 



