178 



PLATHELMINTHES 



Order 2. ASPIDOCOTYLEA. (Fig. 288.) 



Monogenetic and digenetic trematodes which attach themselves to 

 their host by means either of a median row of suckers or a very large 

 ventral sucking disc in which are sucking pits or de- 

 pressions and on the margin of which are often sense 

 organs; hooks and anterior suckers not present and 

 intestine not bifurcate: in the intestine of fishes and 

 reptiles and in mollusks and crustaceans; 1 family and 

 a small number of species. 



Family ASPIDOBOTHRIDAE. 



With the characters of the order: 8 genera. 



Key to the American genera of Aspidohothridae : 



Oi Body cylindrical with a midventral row of suckers. 



1. Stichocotyle 

 02 Large ventral sucking disc containing 3 or 4 longitu- 

 dinal rows of depressions. 

 &i Three rows present. 

 Ci Median depressions very elongate transversely, the 



lateral depressions being round 2. Cotylogasteb 



d All the depressions transversely elongate. 3. Cotylaspis 

 62 Four rows present 4. Aspidogastek 



Fig. 288 



Diagram of the 



Aspidocotijlea 



(Aspidogaster) 



(after Benham). 



1, mouth 



2, intestine 



3, genital pore 



4, ovary 

 5, yolk glands 



6, uterus 



7, testis 



8, ventral suckers 

 or sucking disc. 



1. Stichocotyle Cunningham. Body cylindrical 

 and elongate with a midventral row of 20 to 30 suckers extending the 

 length of the body: 1 species. 



S. nephropis* Cunn. (Fig. 289). Length of adult 17 to 105 mm., 

 with 20 to 27 suckers; length of the larva 3 to 7 mm., 

 with 7 to 22 suckers: adult lives in the liver of Raja 

 and the larva encysted in the intestinal walls of lob- 

 sters and large crabs on the Atlantic coast; Europe. 



2. CoTYLOGASTER Monticelli. Sucking disc long 

 and narrow with 2 lateral rows of round depressions 

 and a median row of very elongate transverse depres- 

 sions; 2 testes; marginal sense organs: 2 species, in 

 the intestine of marine and fresh-water fishes. 



C. occidentalist Nickerson (Fig. 290). Sucking disc with 132 to 144 

 depressions ; length 10 mm. : in the sheepshead in Minnesota. 



Fig. 289 



Stichocoti/le 



nephropia ; 



a larva from a 



lobster 



(Nickerson). 



References 



as in Fig. 288. 



• See "Ueber die geschlechtsreife Form von Stichocotyle nephropis Cunn.," by 

 T. Odhner, Zool. Anz., Vol. 21, p. 500, 1898. 



t "Cotylogaster occidentalis n. sp. and a Revision of the Family Aspido- 

 hothridae," by W. S. Nickerson, Zool. Jahrb. Abt. f. Sys., Vol. 15, p. 697, 1902. 

 "Synopsis of the Trematodes, Part II. The Aspidocotylea," etc., by H. S. Pratt, 

 Am. Nat., Vol. 36, p. 887, 1902. 



