494 A. E. Yerrill — Marine Planarians of Neio England. 



cerebral and frontal ocelli are more or less confused in the prepara- 

 tion, and are unusually far apart, doubtless owing to compression in 

 mounting the specimen ; the distortion of the groups is doubtless 

 due to the same cause ; behind each cerebi'al group there is a rather 

 large isolated ocellus. The posterior or dorsal groups are conspicu- 

 ous, a little elongated, elliptical or oval, somewhat pointed behind ; 

 each is composed of about 12 black ocelli, several of which are con- 

 siderably larger than the others, reniform in shape, with a transpar- 

 ent, lens-like portion on the concave side. 



I have never found another large specimen that can be referred to 

 this species. 



Descri^otion of young specimens: — Several very young individuals 

 were taken at the surface, with towing nets, both at Newport, R. I., 

 and at Wood's Holl, Mass., which apparently belong to this species, 

 but they are all too immature to be identified with certainty, until 

 intermediate sizes shall have been observed. 



One of these young specimens, figured from life, is represented on 

 Plate XL, figure V, in its contracted form ; another unpublished fig- 

 ure of the same individual is considerable longer with the frontal 

 ocelli farther forward, and with the stomach longer and showing 

 eight or nine pairs of lateral branches. The reproductive organs are 

 not distinctly developed. The form is generally obovate or obcor- 

 date, with a distinct emargination in front. The ocelli form six 

 groups; the frontal groups contain each only one or two ocelli; the 

 cerebral groups contain each about three ocelli in a single row; each 

 of the outer or dorsal groups contains three ocelli. (PI. xlii, fig. 7). 



The color is translucent whitish with delicate, pale yellow den- 

 dritic marking and a deeper yellow gastric spot ; the transparent 

 margin is elegantly marked with a row of light golden yellow spots. 

 It is active and graceful in its movements. 



This specimen was taken at the surface of the sea at Wood's Holl> 

 Aug. 16, 1882. 



Tribe, Cotylea Lang. 



Acetajbulum ventral, behind the female opening.* Mouth and 

 pharynx situated between the middle and anterior end of the body. 



* The existence of a ventral acetabulum or sucker is not strictly diagnostic of this 

 group, for certain species of Leptoplana and of Planoeeridce have, also, a ventral 

 sucker of the same kind. But in all the latter groups, so far as I know, the sucker, 

 when present, is in front of the female orifice. 5'erhaps the pit-like depression around 

 the female orifice of certain species of Leptoplanidce is of the same nature and for the 

 same purpose. 



