A. E. Verrill — 3Iarine Planarians of New England. 467 



EustylOChuS, gen. nov. 



Tentacles with ocelli in the sides, or base, or both. Cerebral ocelli 

 variously arranged. Mai'ginal ocelli present. Stomacli branches 

 numerous ; distal branches anastomosed. 



Male and female genital jiores separate, the female ducts opening 

 backward. Seminal vesicle well developed, usually distinctly three- 

 lobed, the middle lobe with a long duct leading to the penis. Penis- 

 sheath short and thick ; penis styliform ; granular gland not prom- 

 inent, closely attached to the penis-bulb, often indistinct. 



Female orifice not far back of the male organ ; it connects with 

 the vagina and with a long, narrow median duct which starts from 

 the orifice and runs forward to or near the gastric region, where it 

 connects with a flask-shaped vesicle, which is probably a sperma- 

 theca or seminal receptacle. The vaginal duct expands into a short, 

 swollen glandular portion, which bends upward and backward upon 

 itself, and receives the uterine ducts. 



This genus agrees externally with Stylochus, but its reproductive 

 organs are very different from those of that genus. 



The only European species which is described as having a similar 

 spermatheca and median duct is Stylochtis macxdatus Quatrefages,* 

 but that dift'ers in other characters. 



EustylochuS elliptiCUS (Giiard) Ven-ill. 



Planocera elliptica Girard, Proc. Boston See. Nat. Hist., vol. iii, p. 251, 1850 (de- 

 scription very brief and imperfect); op. cit., p. 348 (note on its embryology). 

 Embryonic development of Planocera elliptica in Journal Acad. Nat. Science of 

 Philadelphia, vol. ii, p. 307, sep. copies, pp. 7-27, pi. 1-3, 1 854 (details of its embry- 

 ology, but no description of adult). 



Stimpson, Prodromus, in Proc. Philad. Acad. Nat. Sci., vol. ix, p. 25 [5], 1857. 



Lang, Polycladen des Goifes von Neapel, p. 463, 1884 (copy of Girard's I860 brief 

 description). 



Stylochopsis littoralis Verrill, Report on Mar. Invert, of A^'ineyard Sd., etc., pp. 325 

 [31 j, 632 [338], pi. 19, fig. 99, 1873. 



Stylochus littoralis Lang, Polycladen des Goifes von Neapel, p. 453, 1884 (copy of 

 description in work last cited). 



Plate xl, figure 2; plate xli, figures 1, la; plate xui, figures 1, la. 

 Body flat with thin, often undulated, and very flexible margins ; 

 very changeable in form, usually, when creeping, long-oval, ellipti- 

 cal, or oblong; in extension often narrowed anteriorly, but when at 

 rest rounded or subtruncate at the ends ; often with a small median 



* This species, as described and figured by Quatrefages, differs so much from all 

 related forms, that it should, undoubtedly, constitute the type of a new genus, for 

 which I propose the name H^'tcrostyloch^^s. Some of its characters are as follows: 



Trans. Conn. Acad., Vol. VIII. 61 Dec, 1892. 



