A. E. Verrill — Marine Planarians of JSTeio England. 497 



The only specimens of the genus Prosthiostomum that I have 

 found on the New England coast are quite young. Presuming 

 that Girard's species was correctly referred to this genus, my young- 

 specimens may, very likely, belong to the same species, for the 

 ocelli have a similar arrangement. 



Fig. 1. Prosthiostomum gracilt. Young, x 8. 



When living the body is long-elliptical in extension (see cut 1, from 

 life) and quite thin and translucent. The stomach has about four- 

 teen main branches on each side, and these are much divided distally. 

 Those of the anterior pair curve outward and forward around the 

 pharyngeal region and ocelli. The tubular pharynx was only imper- 

 fectly^ seen, and was probably not fully developed. The cerebral 

 ocelli form an interrupted curved row of about four on each side, of 

 which the anterior pair is largest. The posterior or dorsal clusters 

 are each represented by two ocelli, placed obliquely. The marginal 

 ocelli are very distinct, and form a single row around the front edge. 

 The reproductive organs were not developed. 



Color pale yellowish white with darker yellow arborescent mark- 

 ings, due to the gastric branches. Other specimens are light yellow- 

 ish green, with a whitish gastric spot and pale radial lines, and a 

 greenish median line posteriorly. 



Length of the largest about 4""" ; breadth I •25'"'". 



Noaiik, Conn., July 9, 1874; Wood's HoU, Mass., July 25, 1881; 

 New Haven, Conn., Oct. 14, 1892. Boston Harbor (Girard). 



It is probable that Girard's specimens were also immature, and 

 perhaps but little larger than those here described. He does not 

 give the size. 



MONOGONOPORA or TRICLADIDEA. 

 Body generally narrower and relatively longer than in the I>igo- 

 nopora. Sometimes a distinct muscular ventral foot is present. 

 Sometimes a posterior sucker is developed. In some genera there 

 are dorsal tentacles ; in others, frontal lobes. The mouth is gener- 

 ally somewhat behind the middle. The pharynx is generally simple* 



* In the American fresh-water genus Phagocata (Leidy), besides the central pharynx, 

 there is a row of smaller ones along each side, each one arising from the base of a 

 lateral secondary stomach-branch. 



