50 NORTH AMERICAN 



truncated points. There are obscure accessory pieces lying close to the 

 surface of the spicula and forming a double groove in which these lat- 

 ter slide. The ejaculatory duct, though narrow at first, soon becomes 

 nearly half as wide as the body. There are two slender, outstretched 

 testicles extending in opposite directions from near the middle of the 

 body. The anterior one has its blind end about as far behind the base 

 of the neck as the nerve-ring is in front of it. 



Habitat : Alpine lakes, Bald Mountain, Colorado. Formalin to glycerine. 



TERATOCEPHALUS, de Man, 1876. 



Fig. 8, Plate IV. 



ii 



8. Teratocephalus cornutus, n.sp. : : '- : .8 mm. 



i.i i.o 1.8 1.9 i.i 



The thin, transparent layers of the colorless naked cuticle are traversed 

 by about 1500 transverse striae, resolvable into rows of minute dots, which 

 are modified on the lateral fields. These modifications have been seen in 

 all parts of the body, and near the tail consist of two to three irregular 

 longitudinal rows of enlarged dots. The posterior portion of the neck ta- 

 pers but little. The anterior portion becomes convex-conoid toward the head, 

 which bears a lip region more or less set off by a constriction opposite the 

 base of the spreading cephalic setae, which are four in number and 

 submedian in position. Each seta is a little more than half as long as the 

 head. These are connected with a refractive six-ribbed chitinous dome-like 

 framework, which extends back to opposite the middle of the pharynx. The 

 ribs start at the lip region, extend backward, and then join each other oppo- 

 site the base of the vestibule. The chitinous refractive elements at this latter 

 region form a rather distinctly crenate contour around the head. No 

 other setae than the cephalic setae have been seen in any part of the body. 

 The lips appear to be rather thin, and are arched together over the 

 unarmed pharynx, which is somewhat elongated and about half as wide 

 as the base of the head. While it is somewhat irregular in form it 

 is approximately prismoidal or cylindroid and nearly as deep as the 

 head is wide. Its walls are not very strongly chitinized, but more 

 strongly so anteriorly than posteriorly. The oesophagus receives the 

 base of the pharynx, and soon becomes half as wide as the base 

 of the head. In the anterior portion of the oesophagus, a short distance , 

 behind the pharynx are three slightly arcuate, refractive elements, corre- 

 sponding somewhat in curvature with the contour of the front end 

 of the oesophagus. These resemble to a certain extent the refractive ele- 

 ments in the posterior chamber of the pharynx of Plectus. In the present 

 species they are about as long as the pharynx, and are separated a dis- 

 tance about equal to one body width. They are a little wider and more 

 plainly visible anteriorly than posteriorly. The obscure amphids, as 



