4 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 79 



are correlated characters but not characters of generic value. In 

 specimens of C . Ihiffua some were found in which the body was 

 ovoid or piriform in shape and the testes opposite each other, while 

 in others from the same lot these characters conform to the usual 

 type, that is, body linguiform in shape and the testes placed obliquely 

 to the long axis. The same variations were observed in specimens of 

 Rossicotrema donicuin. From these observations it is the writer's 

 opinion that the position of the testes in the Heterophyidae, and 

 possibly also in members of some of the other families, depends upon 

 the shape of the body, and both body shape and position of testes 

 depend upon the state of contraction of the specimens when killed. 



It is frequently dijfRcult to decide upon the relative value of char- 

 acters and to determine which are of generic and which are of 

 specific value. This is especially true with respect to the trema- 

 todes. In checking over the ciiaracters as given for the genera 

 Cryptocotyle Liihe, Tocotrema Looss, Ciureana Skrjabin, Rossico- 

 trema Skrjabin and Lindtrop, and ApophaUus Liihe, only one char- 

 acter appears sufficiently constant to be of generic value, namely, 

 the genital sinus and the arrangement of its accessory structures. 

 In the first three of these genera the genital sinus is a spacious, some- 

 what muscular structure ; the acetabulum is greatly reduced and situ- 

 ated in the anterior wall of the sinus; the genital aperture is post- 

 acetabular; and the genital ducts open into the sinus caudad of the 

 acetabulum at the base of a single, papillalike gonotyl. In the 

 genera RossicotreTna (syn. Cotylophallus) and Apophallus this ar- 

 rangement is entirely diiferent. The genital sinus is reduced in 

 size and its walls weakly developed; the acetabulum is relatively 

 strongly developed and opens into the sinus caudad of the genital 

 pore; the genital ducts open into the sinus cephalad of the acetabu- 

 lum and two papillalike gonotyls are present. Other characters 

 are similar in members of these genera and such variations as are 

 present are regarded as of specific value. It is the opinion of tlie 

 writer, therefore, that all the above-named genera should be reduced 

 to two, namely, Cryptocotyle (syns. Tocotrema and Ciureana) and 

 Apoplwllus (syns. Rossicotrema and Cotylophallus). To the first 

 of these genera, Cryptocotyle^ the following species are referred : 

 C. concava (Creplin), C. lingua (Creplin), C. jejuna (NicoU), C. 

 qu'mqueangulare (Skrjabin), C. cryptocotyloides (Issaichikoff), and 

 G. echinata (von Linstow) ; and to the second genus, Apophallus^ the 

 following species: A. milhlingi (Jiigerskiold), A. donicum (Skrjabin 

 and Lindtrop) (syns. C. venustus and C. simills)^ A. hrevls Ran- 

 som, and A. cranii, new species. 



The following generic diagnoses, to which are appended keys to 

 species, represent the writer's conception of the two genera: 



