472 A. E. Verrill — Marine Planaruins of Nev^ England. 



similar to those of typical Planocera, but the seminal vesicle is free 

 and three-lobed, with the central lobe elongated, tapering backward 

 into a narrow duct that joins the penis, while the side lobes arc con- 

 tinuous with the vasa deferentia ; the penis-sheath is short, thick, 

 conical ; the penis is short, styliform. Female duct runs forward 

 a short distance from the opening and then bends upward and turns 

 back on itself, forming a U-shaped tube. 



Planocera nebulosa Girard. 



Planocera nehidosa Girard, Proceedings Philadelphia Academy Natural Sciences, 

 for 1853, vol. vi, p. 3G7, 1854; Verrill, Report on Invert, of Vineyard Sd., etc., 

 in Annual Report U. S. Com. of Fish and Fisheries for 1871, pp. 325 [31 ], and 

 632 [338J, pi XIX, tig. 100, 1873; Lang, Polycladen, p. 463. 



Plate xl, figure 4; Plate xlii, figure 3. 



Body convex above and rather thick, especially in contraction. In 

 usual extension, broad-elliptical or oblong, but capable of becoming 

 long-elliptical or nearly circular ; edges sometimes thin and undu- 

 lated. Tentacles rather long, slender, tapered, translucent whitish, 

 retractile, situated near together and well back from the front mar- 

 gin ; no ocelli in the distal portion, but a cluster of small ocelli is 

 situated in the base. Mouth and stomach nearly central ; the phar- 

 ynx and stomach have four or five main lobes on each side, and the 

 mouth is a little behind the middle of the stomach ; in some states of 

 expansion the anterior and posterior lobes are somewhat prolonged. 

 The bilobed cerebral' ganglion is situated between or a little before 

 the bases of the tentacles. No ocelli Avere observed in the deep 

 colored living specimens, above described, but when looked for in 

 sections they are found to be numerous. The ocelli in the bases of 

 the tentacles form small rounded clusters, more easil}^ visible from 

 below than from above. Just back of each tentacle and a little 

 more toward the median line there is a larger and more open cluster 

 of ocelli; in the cerebral region there is a pair of small incon- 

 spicuous groups, each containing about two or three ocelli, while a 

 few others are apparently irregularly scattered between and in front 

 of the tentacles. The marginal ocelli are also minute and form two 

 or three rows, some of which extend back to about the middle of the 

 sides. 



Genital orifices two, small, near together, not far from the posterior 

 margin. 



Color somewhat variable. Our specimens were usually olive- 

 green with the paler ground-color showing more or less as whitish or 



