468 PROCEEDINGS OF THE ACADEMY OF [Sept., 



A light stripe generally occupies the area immediately above the 

 main gut which may be bordered laterally by a brownish band. 

 When this last-named variation occurs, light streaks free from pig- 

 •adiate from it to the .margins of the body. A clear spot 

 lly mark? the position of the brain. On the ventral surface 

 pigment is entirely lacking or is present in very slight amounts, so 

 that the more important organs may be seen through the translucent 

 body wall with considerable distinctness. 



The largest specimen measured 11 mm. in length by 5 mm. in 

 width, and is narrowly elliptical in outline (PI. XII, fig. 4). The 

 mouth is situated about one-third of the length of the body from the 

 posterior end of the animal. The penis is directed backward. Both 

 cerebral and tentacle eyes (PI. XIV, fig. 19) occur associated with 

 the brain; none exist on the margins of the body. The tentacle 

 clusters form small groups lateral to the brain, each consisting of 

 about ten medium-sized eyes. The cerebral groups are not sharply 

 differentiated from the others, but in a general way they present a 

 linear arrangement on either side of the mid line bordering the 

 brain and anteriorly expand to form loose clusters in front of the 

 brain. There are approximately 25 small eyes in each of these 

 groups. 



The most conspicuous feature of the digestive system is the 

 posterior position of the pharynx (PI. XII, fig. 4) and external mouth. 

 The first-named organ is about two-fifths the length of the body and 

 is provided with five or six folds of moderate size on each side. The 

 inner mouth is some distance anterior to the true mouth. The 

 main gut is long, rather narrow, and possesses six or seven pairs of 

 lateral intestinal branches, with occasional alternating shorter 

 diverticula, and an anterior and posterior outgrowth along the mid 

 line. Anastomosing immediately commences, resulting in a highly 

 complicated intestinal network. Varying quantities of diatoms 

 and sponge spicules were generally present in the digestive tract. 



In this species the nervous system appears with unusual distinct- 

 ness and has accordingly received more than usual study. The 

 ventral system (PL XIV, fig. 21) conforms closely to the type found 

 to occur in polyclads generally, but in addition to this there is what 

 appears to be an independent network extending over the entire 

 i 1< >rsal surface of the body. It comprises three pairs of main branches, 

 arising from the lateral and anterior surfaces of the brain, that after 



viding repeatedly extend to the margins of the body. Along the 

 i the region of the pharynx, these delicate fibres become 



