466 A. E. Verrill — Marine Planarians of JSTero Migland. 



Stylochus crassus Vemll, sp. nov. 



Description of a specitnen preserved and rendered partially trans- 

 lucent : — Body large, thick, rounded, nearly as broad as long. Upper 

 surface covered with minute, whitish, conical papillae, barely visible 

 to the naked eye. Mouth nearly central. Stomach with about five 

 or six main lateral branches, which have very numerous divisions 

 and anastomose freely distally. A short distance behind the mouth 

 there is a rather large and slightly prominent sucker-like organ or 

 acetabulum. 



Ocelli are minute and very numerous, forming two large, elongated, 

 sub-parallel groups, broadest posteriorly and tapering anteriorly ; at 

 its posterior end each group expands into a wide, roundish, rather open 

 cerebral cluster, which is connected by a narrow band of ocelli with 

 another similar roundish cluster a little farther forward, over the 

 anterior part of the brain, beyond which the groups gradually dimin- 

 ish in breadth to their anterior ends, not far from the front margin 

 of the body. At about the anterior fourth, and a little back of the 

 posterior part of the cerebral groups, and somewhat farther apart, 

 are two low, inconspicuous prominences, which appear to be the re- 

 tracted tentacles ; each of these contains a small group of minute 

 ocelli, not easily distinguishable. 



Marginal ocelli are minute and not very numerous, forming about 

 two rather irregular and indistinct rows anteriorly, but the margin is 

 somewhat abraded and some of its ocelli may have been destroyed. 



Most of the interior of the body is densely filled with small ova. 

 The density, thickness, and opacity of the tissues render the study of 

 the reproductive organs impossible, except by sections, for which my 

 single specimen is not suitably preserved. 



Color of the preserved specimen dull brown, covered above with 

 small white specks, due to the papillae. 



Length and breadth of the alcoholic specimen about 25"""; thick- 

 ness 2 to 3'""'. 



Station 2732, U. S. Fish Com. steamer Albatross, Oct. 26, 1886, 

 N. lat. 37* 27'; W. long. 73° 33', in 1152 fathoms, dark green mud. 



Only one specimen was taken. It is remarkable for its great size, 

 thickness, and solidity. I refer it to this genus only provisionally, 

 because its reproductive organs are unknown. I detected only a 

 single genital pore, of small size, near the posterior end, but a second 

 may exist, for the specimen is broken and not well preserved in that 

 region. The arrangement of the ocelli is sufficient to distinguish it 

 from all other American species. 



It is possible that it lives at the surface among floating algse, and 

 not at the bottom. 



