SIXTEN BOCK, TWO NEW COTYL. GEN. OF POLYCLADS 3 



The two pairs of large cerebral eyes are situated close 

 to the dorsal epithelium, just beneath the dorsal musclc 

 layers of the body. They ha ve their pigment cups directed 

 so tbat the light falls into them from ahove. On the lateral 

 side of each pair there is one much smaller eye. These two 

 small eyes are very close to the brain and in that way si- 

 tuated beneath the layer of pigment above the brain which 

 will be mentioned låter on. On account of this position 

 in the immediate vicinity of the brain, which as usual 

 approaches the ventral side, the pigment cups are open on 

 their ventral side. Thus the light can reach the sensible rods 

 only from the ventral side and must then pass through the 

 brain. These small eyes are innervated by the same nerves 

 which run to the double pairs of large eyes. The two 

 pairs of large eyes correspond to those in Stylostomum. 



The external mouth is situated at the end of the first 

 third of the body. It leads into a pharyngeal chamber which 

 is rather comprehensive to belong to a cotylean polyclad, 

 i. e. occupying nearly one third of the body length. 



The relatively large sucker is at the end of the third 

 quarter of the body. 



The epithelium of the body is high and provided with 

 dense but short cilia. In the dorsal epithelium there is 

 the above-mentioned brown dense pigment which also occurs 

 in the muscularis and parenchyma beneath the dorsal epi- 

 thelium. 



It is noteworthy that the long and slender rhabdites are 

 numerous only on the dorsal side. On the ventral side 

 another kind of acidophilous gland cells is abundant; these 

 produce a granular secretion. Another interesting feature is 

 the occurrence of nematocysts in the dorsal epithelium. 

 Hitherto nematocysts have been met with amongst polyclads 

 only in Stylochoplana tarda(hy v. Graff) and Anonymus vi- 

 rilis (by Lang, 1884). From this occurrence the conclusion 

 can be safely drawn that this polyclad feeds on Cnidarians, 

 probably Hydroids. These cnidarian capsules, already burst 

 or undamaged, occur in the alimentary canals both in the 

 lumen and in the intestinal epithelium cells as well as in the 

 parenchyma of the body. As the basement membrane is 

 rather thin they find no great difficulty in penetrating 

 through it. Obviously these unburst capsules serve as de- 



