54 PROCEEDINGS OP THE NATIONAL MUSEUM vol.81 



Stiles and Hassall (1894) examined the trematodes of the Leidy 

 collection and redetermined the specimens reported from the nasal 

 passages as Opisthotrenna cochleare Fischer. A part of the ma- 

 terial, two specimens, was retained in the United States National 

 Museum collection, and it is upon these that the foregoing descrip- 

 tion of Opisthotrenia cochleotrema is based. 



These specimens are sexually mature, but somewhat smaller than 

 those reported by Leidy. One of them was stained and mounted 

 whole; the other was stained and sectioned. The description given 

 above is a composite one, the details being obtained from the sec- 

 tioned specimen. 



Opisthotre7na cochleotrema differs in a number of respects from 

 0. dujonis (Leuckart) { = 0. cochleare Fischer), so that there ap- 

 pears to be no doubt that they are distinct species. O. cochleotrema 

 is provided with a muscular rim similar to that described for Pid- 

 monicola puhnonalis (von Linstow) ; the intestinal ceca are slender 

 and uniform in diameter, serpentine, and their blind ends converge ; 

 Laurer's canal is absent; and the terminal part of the uterus is not 

 expanded to form an egg reservoir. In O. dujonis the body is not 

 provided with a muscular rim ; the intestinal ceca are not of uniform 

 width, only slightly sinuous, and their blind ends diverge; Laurer's 

 canal is present; and the distal part of the uterus is expanded to 

 form an egg reservoir. Other differences may be easily seen by com- 

 paring the descriptions and figures of the two species. 



Fischer's (1883) figure of Opisthotrema cochleare { = 0. dujonis) 

 leaves the impression that the principal branches of the excretory 

 system open separately and in this connection he states " indem 

 wahrscheinlich nicht eine, sondern zwei Miindungsstellen vorhanden 

 diirften, die der ventralen Seite angehoren und jederseits unterhalb 

 der Darmschenkel liegen." Poche (1926) doubts the presence of two 

 excretory pores in this species, but Fuhrmann (1929) believes that 

 two openings should be present and has indicated in the figure of O. 

 cochleare (" nach Fischer '') just where these openings should be 

 located. The study of serial sections of O. cochleotrema has shown 

 that the position of the excretory pore in this species is essentially 

 the same as that in members of the famil}'^ Notocotylidae * and 

 Pronocephalidae. In view of this fact it appears reasonable to as- 

 sume that the position of the excretory pore in O. dujonis will be 



* In Pochc's (1926) classification of the trematodes, the monostomes belonging to the 

 families Notocotylidae, Pronocephalidae, Opisthotrematidae, and Rhabdiopoeidae are placed 

 In the super-superfamily Notocotylida. Since groups of the rank of super-superfamily 

 have not been recognized by helminthologists and are unnecessary at present, the writer 

 proposes at this time the new superfamUy Notocotyloidea, to replace the super-superfamilj 

 Notocotylida Poche. 



