I. RENIFER gen. nov. 



The first three worms described in this paper, of which two are new to science, 

 are all very closely related to one another and were found in similar localities, the 

 mouth and air-passages of common North American snakes. They are also so closely 

 allied to a worm recently described by Looss ('99, p. 708) under the name of Styph- 

 lodera solitaria, which was found by him in the intestine of Thalassochelys corticata, 

 a sea-turtle, and to one recently described by Volz ('99, p. 231) from the lung of 

 Heterodon platyrhinus and named by him Distomum zschokkei, that no doubt 

 exists in my mind that all five species should be included in the same genus. This 

 genus cannot well be Styphlodera, for reasons I shall give later on, and I have, 

 therefore, created a new genus to contain them. The new genus may be given 

 the following characterization. 



Renifer gen. nov. Small distomes with body more or less elliptical and cov- 

 ered with minute spines or scales. Mouth subterminal; acetabulum somewhat 

 larger than oral sucker and in anterior half of body. Pharynx present; oesophagus 

 short or wanting; intestinal caeca reach about to the middle of the body or a little 

 past it. Excretory vesicle very large, Y-shaped, extending into the forward end 

 of the body. Genital pore in front of the acetabulum often to the left or the right 

 of the median line. Testes two, usually lobate, in the same transverse plane near 

 the middle of the body; cirrus-sac often long, containing a vesicula seminalis which 

 bends on itself. Ovary just posterior to the acetabulum and in front of the testes; 

 yolk-glands lateral in position and occupying the middle third of the body; Laurer's 

 canal present; uterus composed of a descending and an ascending limb, and extend- 

 ing to the hinder end of the body; receptaculum seminis absent or minute. Parasitic 

 in the mouth or air-passages of snakes and in the intestines of turtles. 



Type: Renifer ellipticus Pratt. Additional species: R. elongatus Pratt, R- 

 variabilis (Leidy) Liihe, R. solitarius Looss, R. zschokkei Volz. 



II. RENIFER ELLIPTICUS sp. nov. 



This worm (PL IV, Fig. 1) was found in the mouth of Heterodon platyrhinus, a 

 common non-poisonous snake. It is a small worm, elongated in form and elliptical 

 in outline; its dorsal surface is cylindrical, its ventral surface flat, the cross-section 



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