A. Til. Verrill — Marine Planarians of New England. 487 



siphon-shaped, with an external opening at each end. Its anterior 

 opening is very near the male orifice (in contracted specimens often 

 in the same depression); the posterior orifice is smaller and consider- 

 ably farther back. A special spermatheca is wanting, or may be 

 formed by a dilation at the anterior bend of the vagina, and not 

 much specialized. 



The single European species ( T. cephaloplithalmns).^ for which this 

 genus was constituted, is a long and narrow form, with the groups 

 of ocelli all confused, while our two species are broad and stout 

 forms, with the four main clusters of ocelli clearly distinct, and ar- 

 ranged much as in Leptoplana and Cryj^tocelis, from which they dif- 

 fer but little in general appearance, when living. From Leptoplana 

 they ai'e, however, easily distinguished by the presence of numerous 

 marginal and fi'ontal ocelli, and by the peculiar structure of the gen- 

 ital organs. In the structure of the reproductive organs, and espe- 

 cially in having two orifices for the female duct, both of our species 

 agree well with the type-species of Trigoiioporus. 



The cerebral ganglions and main nei've-trunks in both of our spe- 

 cies are distinctly pale red in life, the color resembling that of the 

 nervous system of certain nemerteans belonging to the genera Lineus 

 and Cerehratulus. This observation was repeated many times, and 

 in different years, so that it can scarcely be due to any temporary 

 cause. I have not observed a red color in the nervous system of any 

 other planarian. 



Trigonoporus folium Veniii. 



LeptojjJana folium Yerrill, Marine Invert, of Vineyard Sound, etc., pp. iVA'l [?>:-i8], 

 1873 ; Lang, op. cit.. p. 512 ; copy of original description. 



Pl.-^te xli, figures 5, 5a, 6; Plate xlii, figures 5, 5a, 56; Plate xliv, figures 

 4, 4a, 46, 4c, 4rf, 56, 6, 7. 



Description of living specimens : — Body very changeable in form, 

 rather flat, leaf-like, in extension oblong-elliptical or ovate, and 

 usually nai'rowest anteriorly, capable of contracting to short, rounded 

 or broad-ovate forms ; mai'gins more or less undulated, when in rapid 

 motion. 



Ocelli small and rather inconspicuous ; the dorsal groups are sit- 

 uated at about the anterior fourth or fifth ; the cerebral groups are 

 elongated, irregularly fusiform, there being two broader portions, 

 united by a narrower one, in the middle of each ; they taper to a 

 point at both ends, with numerous minute ocelli in the broader parts, 

 near the middle and over the front and posterior ends of the gan- 



