510 A. E. Veri'ill — Marine Planar lans of New England. 



Length about l-S""'-; breadth 0-35 to 0-50'""\ 



Newport, R. I., at low-water mark, among algae, July 29, 1880. 



This species is only provisionally referred to the genus Aphanos- 

 tonia, for its internal anatomy was not studied. The specimens 

 were lost. 



Aphanostoma olivaceum sp. nov. , 



Plate xui, figure 9. 



Body ovate, broadest anteriorly, rather thick, convex. Otocyst 

 conspicuous, at about the anterior eighth. Mouth rather behind 

 the middle ; digestive cavity large, behind the middle ; in the ex- 

 ample figure it contained an amphipod crustacean. 



The ovaries are large, lateral; posteriori}', the oviducts are tilled 

 with two or three rows of large ova, which are dark green in color. 

 The female orifice is about midway between the posterior border of 

 the digestive cavity and the male orifice. The latter is near the 

 posterior margin, in the center of a pale spot. It is flanked on each 

 side by two small vesicles (probably seminal vesicles) ; two larger 

 saccular organs (perhaps the posterior part of vasa deferentia) run 

 forward and diverge, but their nature was not certainly ascertained' 

 owing to the dark color of the integument. The form and structure 

 of the penis and spermatheca were not observed, for the same reason 



Color dark olive-green, or brownish green. 



Length 2'""'; breadth about 1-5"'". 



Provincetown, Mass., at low-water mark, among filamentous algse, 

 Aug. 14, 1879. 



This species is referred to Aphanostoma only provisionally, for 

 its reproductive organs are imperfectly known. It has considerable 

 resemblance to certain species of Mecynostoraa. 



Polychoerus Mark. 



Festschrift fiir Leuckart, p. 298, Oct.. 1892. 



Body flattened, changeable in outline, usually cordate or ovate, 

 narrowest anteriorly, emarginate or bilobed posteriorly, with one to 

 five slender, contractile caudal cirri. The lateral margins are usually 

 not inflexed. Mouth central or nearly so, with simple muscular 

 margins. No proper pharynx. Digestive cavity large, separated 

 posteriorly from the genital area by tissues more dense than those 

 of other parts. 



Otocyst small, round, sometimes indistinct or wanting; otolith 

 cup-shaped. 



Brain distinctly bilobed; each ganglion is somewhat stellate in 

 form, and gives off three main nerves: anterior, lateral, and poste- 



