POLYCLADS OF THE ATLANTIC COAST' HYMAK 467 



Section Schematommata Bock, 1913 



Definition. — Acotylea "without marginal eyes; eyes in cerebral and 

 tentacular clusters, well back from the anterior margin. 



Family LEPTOPLANIDAE Lang, 1884 (emend. Bock) 



Definition. — Schematommata with flat, moderately elongate bodies, 

 often expanded anteriorly ; tentacles present or absent ; prostatic vesi- 

 cle when jDresent always interpolated ® ; usually brown above, seldom 

 white ; uteri confluent anterior to the pharynx. 



Genus STYLOCHOPLANA Stiiapson, 1857 



Definition. — Leptoplanidae with distinct seminal vesicle and pro- 

 static vesicle; the ejaculatory duct from the seminal vesicle does not 

 penetrate into the prostatic vesicle. 



STYLOCHOPLANA ANGUSTA (Verrill. 1893) 



Leptoplana angusta Verrill, 1893, p. 485, pL 40, fig. 8; pL 44, figs. 2, 3 {not 

 Stylochoplaiw angusta Paloinbi, 1928, or Leptoplana angusta Pearse, 1988, or 

 Leptoplayia angusta Pearse and Littler, 1938). 



Stylochoplana angusta Hyman, 1939a, p. 139, figs. 10, 11. 



Reniar'ks. — I have already described this species, but one point was 

 left unsettled — whether there are two exits to the genital atrium. 

 P'ortunately four more of the specimens collected by Verrill were 

 found in U. S. National Museum material, and there is also a small 

 specimen mounted whole in Pearse's Florida material. Two of the 

 Verrill specimens and the Florida specimen were sectioned; the latter 

 showed but one genital pore ; of the Verrill specimens, one was in poor 

 shape but the other clearly has two genital pores, one in the usual 

 ventral position, the other opening posteriorly into the notch. It seems 

 probable that only the riper specimens have the second opening. This 

 peculiarity together with the far anterior position of Lang's vesicle 

 would justify the creation of a new genus for tliis species. I forbear 

 to do so, since Palombi, who has made a special study of the genus 

 Stylochoplana, informs me in a letter that he proposes to create such 

 a genus. The extra genital pore of the species appears to represent 

 a very short ductus vaginalis, a structure not uncommon in the family 

 Leptoplanidae (see below, p. 475). 



Pearse and associates confused three different species under the 

 name Leptoplana angusta and Pearse and Walker list angusta among 

 New England polyclads. It is not, however, a New England form, 

 since Verrill found his specimens on the bottom of a whaling vessel 



•The prostate is said to be interpolated when it forms part of the male canal so 

 that the sperm passes through its lumen. 



