1912.] NATURAL SCIENCES OP PHILADELPHIA. 471 



with the anterior end broadly rounded or even truncate, while the 

 posterior extremity is narrowed. It measures 9 mm. in length by 

 5 mm. in width. The mouth is placed slightly behind the centre of 

 the body. The penis is directed backward. Nuchal and marginal 

 tentacles are wanting. Eyes occur in four distinct clusters (PI. 

 XVIII, fig. 43), the tentacle pair, each consisting of seven or eight 

 large ocelli, and a pair of cerebral groups. The last-named com- 

 prise approximately thirty relatively small eyes in each set, forming 

 an elongated patch bordering the brain. No eyes occur on the 

 margins of the body. 



The digestive system (PL XIII, fig. 8) presents no especially novel 

 features. The external mouth leads into a considerably folded 

 pharynx whose length is between one-third and one-half that of the 

 body. Laterally it is produced into seven pairs of lateral diverticula. 

 Directly dorsal to the outer mouth the opening from the pharynx 

 leads into the mid-gut, which in turn possesses seven pairs of lateral 

 intestinal branches together with an anterior offshoot leading forward 

 across the brain. This system ramifies chiefly by means of simple 

 branching, but occasional anastomoses were seen, especially in the 

 neighborhood of the pharynx. 



The brain occupies a position about one-fifth the length of the 

 animal from the anterior end of the body. Neither it nor the main 

 nerves are distinct, and accordingly have not been studied to any 

 considerable extent, though sufficiently to decide that all conform 

 to the customary type. 



The testes are rather uniformly distributed, and the sperm canals 

 leading from them appear to form an anastomosing system. The 

 vasa deferentia are likewise delicate and somewhat difficult to follow, 

 though their general features appear with considerable distinctness. 

 From the seminal vesicle (PI. XIII, fig. 8) each swings outward and 

 forward, becoming somewhat anastomosed, and when they have 

 reached points lateral to the uteri and midway between the mouth 

 and the posterior end of the pharynx they turn sharply backward, 

 pass inward toward the mid line and fuse immediately behind the 

 pharynx. The remaining features of the male reproductive system 

 (PL XIII, fig. 14) are relatively simple. From the seminal vesicle, 

 which is adjacent to the posterior end of the pharynx, the ejaculatory 

 duct pursues a short and direct course posteriorly to the penis. 

 This last-named organ is enclosed within a spherical, muscular 

 sheath from which a comparatively long, loop-shaped tube leads to 

 the common reproductive pore. 

 31 



