468 A. E. Verril! — Marine Planarians of N'ew England. 



posterior lobe, but at other times with a notch in the middle of the 

 posterior margin ; frequently the breadth exceeds the length, but 

 more commonly it is less than half. The tentacles are small, round, 

 elongated and tapered in full expansion, often obtuse in partial re- 

 traction, translucent white, each containing an elongated, crowded 

 group, extending from the base nearly to the tips, consisting of about 

 twelve to twenty-live small, but conspicuous, black ocelli. The ten- 

 tacles are situated at about the anterior fourth of the body, and are 

 usually separated by a distance equal to about one-fourth of its 

 breadth, but the relative positions of the tentacles change according 

 to the degree of extension. Frontal and cerebral ocelli usually about 

 eight to twelve, often more in the largest specimens. They usually 

 form four or six small paired groups ; the two groups most in ad- 

 vance of the tentacles and situated over the frontal nerves sometimes 

 contain three or four ocelli each, but more commonly only two ; the 

 next pair of groups, which are nearer together and situated between 

 or a little in front of the tentacles, about over the apex of the cere- 

 bral ganglions, or near the base of the large frontal nerves, usually 

 contain each only two or three ocelli, one of which is larger than 

 the othei's, but in some adult specimens they contain four or live 

 ocelli, the mimber in that case often varying in the right and left 

 clusters ; a little farther back and directly over each gangloin there 

 are often one or two pairs of ocelli ; occasionally there are others 

 placed singly over the posterior part of the gangloins. Young ex- 

 amples often have only the two front pairs of groups, each consist- 

 ing of two ocelli. Marginal ocelli numerous, black, easily seen with 

 a lens ; they are most numerous on the anterior margin, where they 

 are arranged mostly in two or three or more irregular rows along 

 the pale border ; they extend back to the middle of the sides or be- 

 yond, gradually decreasing in numbers backward ; a few ocelli, 

 which are usually loosely arranged somewhat in radial rows over the 



Heterotsylochus, gea. nov. 



Tentacles with lateral ocelli ; cerebral ocelli form two groups ; apparently no 

 marginal ocelli. Main stomach-branches few. Genital openings separate. Vasa 

 deferentia large, discharging into the ejaculatory duct; seminal vesicle large, rounded, 

 sessile. Muscular penis-bulb pyriform. A long, narrow, median duct (vagina Quatr.), 

 runs far forward from the female orifice and expands into a flask-shaped seminal 

 receptacle or spermatheca near the male organs; a swollen egg-duct also connects 

 with the female orifice. 



Type H. maculatus (Quatr. sp.) from Saint Malo, under stones. (See Ann. des sci. 

 nat., iv, p. 144, pi. iv, figs. 3, 3a; pi vi, fig. 2, anatomy). 



Stylochoplana macvlafa Lang, op. cit., p. 459. 



