NO. 2267. 



NEW BRANCHIOBDELLID WORMS— ELLIS. 



247 



from the North Carolma specimens or the original description of 

 BrancMohdella pulcherrima Moore (=X, pulchernmus (Moore)). 

 Thirty of these 37 worms have the dental formula 5-4, and none of 

 the 37 have the dental formula 3-3. In view of the fact that inter- 

 grading individuals with dental formula ^-3 may be found in sub- 

 sequent collections (worms with dental formula 4-3 were found 

 in collections of the closely related species, X. formosus Ellis) 

 these 37 worms luive been assigned to Moore's species X. pulchcrri- 

 mus, and the dental formula of this species is considered as varying 

 from 3-3 to 5-5. The jaws of the United States National Museum 

 specimens were of types II and III, depending upon the number of 

 teeth present. Moore's figure^ may be interpreted as a jaw of 

 type II without the teeth of the "c" order. It is possible that the 

 North Carolina worms with the dental formula 3-3 and the West 

 Virginia worms with dental formula 4-4, 5-4, and 5-5 may represent 

 two distinct subspecies. As only two specimens from North Caro- 

 lina were examined, a complete comparison on this point could not 

 be made. The variations in the number of teeth in the worms 

 studied are tabulated below. 



Table 2. 



XIRONOGITON, new genus. 



Branchiobdellid worms having testes, nephridia, sp«"^'matheca, 

 pharj-ngeal diverticula and intersegmental septa like those oi the pre- 

 ceding genus, Xironodrilus; a distinct accessory sperm tube joining 

 the atrium in segment VI; segment IX much reduced so that in 

 dorsal view the body appears to be composed of eight or fewer seg- 

 ments; alimentary canal looped once or twice in segment VII, and 

 in mature worms asymmetrically placed in segment VI, where the 

 intestine is pushed to one side by the enlarged reproductive organs; 



iproc. Acad. Nat. Sci. Phila., vol. 45, 1893, fig. 2c. 



