72 PROCEEDINGS OF THE NATIONAL MUSEUM vol. los 



Family Stylochidae Stimpson, 1857 

 Genus Ommatoplana Laidlaw, 1903 



Mexistylochus Hyman, 1953, p. 291. 



Definition: Stylochidae of oval form and stiff consistency; dorsal 

 surface usually covered with tubercles; with numerous cerebro frontal 

 eyes; mouth at the posterior end of the pharyngeal cavity; male appa- 

 ratus as in Stylochus but penis sheath present; female apparatus with a 

 vaginal duct, opening separately to the exterior well behind the female 

 gonopore. 



Type species: Ommatoplana tuherculata Laidlaw (1903b). 



Ommatoplana oceanica, new species 



Figure 3,b,c 



Material: Two specimens, both damaged, are present in the ma- 

 terial, collected by P. E. Cloud at Saipan in the Marianas Islands 

 May 6, 1949. One specimen was represented by the posterior half 

 only and this has been sectioned sagittally. The other specimen, 

 retained as a whole mount, has a piece missing from one side. 



Whole mount features: The whole mount is represented in figure 

 3,c. The form is broadly oval, 17 mm. long by 12 mm. wide. The 

 dorsal surface is studded with low tubercles or warts that are larger 

 centrally and diminish in size to the periphery, although very small 

 warts also occur between the larger ones. The color appears light 

 brown, possibly white in life, with dark brown or black tubercles. The 

 margin is completely encircled by a band of eyes, broader anteriorly. 

 There is present a pair of small tentacles rather far back from the 

 anterior margin, and the small eyes in and around the tentacles may 

 be regarded as tentacular clusters. There are two elongated cerebral 

 clusters of many small eyes. The entire anterior part of the body, 

 comprising well over one-third of the body surface, is dotted with 

 small eyes extending to the marginal band. The pharynx could not be 

 seen in the whole specimen, but in sections it appears elongated and 

 somewhat posteriorly located. The intestinal branches appear anas- 

 tomosed into a small-meshed network. The mouth could not be seen 

 on the whole mount, but sections showed that, as in the type species, 

 it is located at the posterior end of the pharyngeal cavity which leads 

 to it by a narrow tube. 



Histology: Much of the description of the type species is devoted 

 to the general histology and a good figure is given of the general 

 appearance of a section. As shown in this figure, the dorsal tubercles 



