THE BEANCHIOBDELLID WOEMS IN THE COLLEC- 

 TIONS OF THE UNITED STATES NATIONAL MUSEUM, 

 WITH DESCRIPTIONS OF NEW GENERA AND NEW 

 SPECIES. 



By Max M. Ellis, 



Of the University of Colorado, Boulder, Colorado. 



The Branchiobdellid worms discussed in this paper include those 

 in the United States National Museum collection and worms from 

 various localities, obtained in many cases through the personal 

 efforts of various collectors. It is a pleasure to thank these col- 

 lectors and credit the specimens to them under the proper species. 

 The writer is indebted particularly to the United States National 

 Museum for the loan of specimens; to ^ 



Prof. J. Percy Moore, of the University ^ .^ j 



of Pennsylvania, for valuable material V^N. y"^^/ 



for comparison; to Prof. Frank Smith, ^ \^,.....^y/. c 



of the University of Illinois, for va- h<'^>c 



rious favors in connection with this Ix^ "-. 



work; and to Dr. Walter Faxon, of b' '/ 



Harvard University, for the determina- ^p,Q i._sagittal section through a 

 tion of many of the host species of tooth of the " b " order of the 



f, , UPPER JAW OF XIRONOGITON OREGO- 



CraynSn. NENSIS OREGONENSIS ELLIS FROM 



In studying these worms special at- eugene, oregon. portion below 



, , 1 . 1 ab=anterior face, portion above 



tention was given to the ]aw char- dc=supportino face, portion be- 

 acters and to the variation in the low ef=-dental face, q=base of 



, c X j1 4 -ii. 1 i." JAW, H>= DENTAL RIDGE. 



number of teeth. A sagittal section 



of either jaw is roughly triangular in outline, so that the jaw 

 may be considered as having three faces. These have been termed 

 the supporting face (fig. 1, portion above do), the anterior face (por- 

 tion below ah), and the dental face (portion below ef). When the 

 jaw is in place the supporting face and a considerable portion of 

 the dental face are imbedded in the wall of the pharynx, the teeth 

 are directed caudad down the pharynx, and the anterior face lies 

 parallel to the long axis of the body in the lumen of the pharynx. 

 When the jaw is in use the teeth and part of the dental face are 

 swung into the lumen of the pharynx by a movement of the entire 

 jaw. Of these three faces of the jaw, the anterior is the most regu- 

 lar. The anterior or cephalic margin of the supporting face has 

 been designated the base of the jaw {g) and the posterior or caudal 



Proceedings U. S. National Museum. Vol. 55— No. 2267. 



62055— 20— Proc.N.M.vol.55 17 241 



