462 A. E. Verrill — Marine Planariana of New England. 



Family, Planocerid^e Lang. 



Notoceridece Diesing, Syst. Helm., p. 215, 1850. 



Planoceridce and Stylochidce Stimp., Prodromus, pp. 4, 5, in Proc. Acad. Nat Sci. 

 Philad., vol. ix, pp. 22, 23, 1857. 



Two dorsal tentacles, usually containing ocelli. Mouth situated at 

 or near the middle of the body. Male copulatory organ directed 

 backward. Marginal ocelli present or absent. Cerebral ocelli gen- 

 erally present. 



StylochuS (Ehrenberg) Lang (restr.) 



Stylochus (pars) and Stylochopsis Stimpson, op. cit, p. 22 [8], 1857. 

 Stylochus (pars) Lang, op. cit., p. 447. 



Body very changeable, usually ovate or elliptical and flat in full 

 extension, but thicker and firmer than usual in this group when con- 

 tracted. Two dorsal tentacles, each containing a conspicuous group 

 of ocelli, and situated rather far back from the anterior end of the 

 body. Other groups of ocelli are situated between, or in front of the 

 tentacles over the cerebral ganglions and frontal nerves ; others form 

 submarginal rows, most numerous anteriorly. The pharnyx is fur- 

 nished with several accessory plicated lobes or pouches, Male and 

 female genital openings are situated close together near the poste- 

 rior end of the body and in the typical species open into a common 

 external pit or pore ; female copulatory pouch apparently wanting 

 in the typical species ; accessory vesicle or spermatheca absent or 

 small. 



The following species are referred with some hesitation to this 

 genus, with which they agree well in external characters. They 

 differ from the figures and descriptions given by Lang of the Euro- 

 pean species in the structure of both male and female copulatory 

 organs, especially in having two distinct genital openings, with the 

 female duct opening backward. I have, accordingly, modified the 

 generic characters so as to include them. But when their anatomy 

 becomes better known it may be found that they belong rather with 

 the new genus Eustylochiis, described below. At present it seems 

 best to put them in the older genus, which still evidently includes 

 very diverse species. 



One of these peculiar forms T have separated (see p. 466, note) 

 as a new genus, Seterostylochus. 



The anatomy of both the type-species of Stylochopsis Stimp., is 

 still unknown. There is nothing in the original diagnosis of that 

 group to distinguish it from Stylochus^ as now restricted. 



