POLYCLADS OF THE ATLANTIC COAST^ HYMAN 491 



Eyes. — Band along anterior margin usually distinctly paired, nar- 

 row median region without eyes; about 30-75 eyes in band on each 

 side; band extends around sides of anterior end to level somewhat 

 behind brain. Cerebral eyes in paired elongated clusters of about 

 10-20 eyes each (Pearse, 1938, fig. 34). 



Color. — Cream color or dirty white, yellowish brown toward median 

 line. 



Digestive system. — Figured by Pearse, 1938, fig. 34. 



Reproductive system-. — One of Pearse's specimens was sectioned, 

 but the sections were so poor that I am not able to add anytliing to 

 his account and figure of the reproductive system (1938, fig. 34). 

 The members of this genus are almost identical in the details of the 

 sexual system. 



Distnhution. — Florida to North Carolina. 



Habits. — Associated with sponges, shells, oysters, and pile animals. 



Remarks. — The species of Prosthlostomum are very difficult to dis- 

 tinguish. P. lohatwm appears to be a valid species of the genus; it 

 differs from most members of the genus in the paired arrangement 

 of the eyes of the marginal band, although this is not evident in 

 every specimen. 



SPECIES OF UNCERTAIN POSITION 



In this paper all the species of Girard and all but one of the species 

 of Verrill are accounted for and allocated to the proper genera. It 

 is impossible at present to evaluate Stylochus crassus Verrill, 1892. It 

 was described from a single specimen taken by the Albatross at 6,900 

 feet off the Maryland coast. As Verrill gave no figures, little can be 

 decided about it until some fortunate chance shall yield another 

 specimen. 



