507] LARVAL TREMATODES—CORT 61 



4. Stylet glands not more than four on each side and arranged in 

 rows on each side of the acetabulum. 



5. Digestive system undeveloped except for a short prepharynx 

 and a small pharynx. 



Three European and three Egyptian cercariae are sufficiently known 

 to be included with any certainty in this group. The European forms 

 are Cercaria pugnax La Valette, Cercaria microcotyla Filippi, and Cer- 

 caria siibulo Pagenstecher (for description of these forms see Liihe, 1909 :- 

 196-198), and the Egyptian forms are Cercaria celluosa sp. inq., Cercaria 

 pusilla sp. inq., and Cercaria exigua sp. inq. all described by Looss 

 (1896:227-232). Insufficiently known forms which from their small size 

 and the shape of the sporocysts may belong to this group are Cercaria 

 chlorotica Diesing, Cercaria alba Ercolani, and Cercaria punctum Erco- 

 lani. Cercaria parva Ercolani in which the oral sucker is smaller than 

 the acetabulum agrees in its other characters with the members of this 

 group. 



The Microcotylous cercariae are best distinguished from each other 

 by the size and shape of their stylets. Cercaria leptacantha agrees most 

 closely with the Egyptian species Cercaria exigua. It is larger than this 

 species however, the suckers differ in size and the ratio of size, and the 

 stylets differ in size and shape. 



Only one suggestion is found in regard to the adults of this group. 

 Looss (1896 :232) considers that the three cercariae of this type described 

 by him may belong to some small distomes found in Egypt in the intes- 

 tines of chameleons and lizards. He offers no particular grounds for 

 this hypothesis. 



Last will be considered a form of the Xiphidiocercariae which 

 seems to be different from all forms previously described. The livers 

 of three out of ninety-one specimens of Physa anatina from Manhattan, 

 Kansas, were infected with sausage-shaped sporocysts (Fig. 72) which 

 contained cercariae in different stages of development. I propose for this 

 species the name Cercaria brevicaeca from the fact that the intestinal 

 ceca are very short. 



Cercaria brevicaeca moved clumsily and irregularly while swimming 

 and did not creep by aid of its suckers. The infection was very slight 

 and all the observations were made from living specimens. None of the 

 cercariae were observed to live more than two or three hours after removal 

 from the snail. 



