38 ENTOZOA. 



in breadth. The egg represented in the accompanying plate (Fig. 

 6) was obtained from an amphistome found in the paunch of a 

 Zebu formerly living in the London Zoological Society's Menagerie. 

 Fig. 7 represents a group of sperm- cells or corpuscles from the 

 testes. The latter organs, according to my own dissections, are 

 not oval, but lobed, and, therefore, I have in this particular modified 

 the otherwise generally accurate representation of Blanchard. But 

 the most striking appearances in the accompanying illustration 

 have reference to the pouched coecal ends of the minute twigs of the 

 water- vascular system, which, if Blanchard' s drawings are correct, 

 entitle him to the credit of having first pointed out such a mode of 

 origin in these vessels. Dr. Gruido Wagener has indicated a similar 

 arrangement in connection with the water- vascular system in Holos- 

 tomata, but my own recent inquiries enable me to assert most 

 positively that no such enlargement of the ultimate ramifica- 

 tions obtains in the genus Fasciola. The general arrangement of 

 these vessels in the last-named genus is indicated in one of the 

 figures given in the Frontispiece, but I reserve a more particular 

 account of this system until I specially treat of the anatomy of the 

 common fluke in the Second Part of this work. In the meantime 

 I would call attention to the differences observable in the arrange- 

 ment of the vessels of Fasciola as compared with the same series 

 of structures in Amphistoma. Long ago, Laurer pointed out the 

 course pursued by the two main channels, from the head down- 

 wards on either side of the body, and their ultimate communica- 

 tion by means of a pyriform reservoir, as here shown on the dorsal 

 surface of the Amphistome. Several authors, such as Bojanus, 

 Diesing, Laurer, and Blanchard, have described a nervous system 

 in this genus, and Laurer even affirmed that he had seen gangli- 

 onic enlargements along the course of the principal nerve-trunks 

 both here and in other trematodes. It is very doubtful, however^ 

 if any lateral ganglia exist. The larvse of Amphistoma conicum 

 have not yet been identified, but in all likelihood they dwell in 

 the bodies of water-snails. This may be inferred from the circum- 



