476 PROCEEDINGS OF THE NATIONAL. MUSEUM vol.89 



hoped to avoid making a new genus for the present species by plac- 

 ing it in an existing leptoplanid genus with a ductus, but it does 

 not seem to fit well enough into any of the three mentioned, al- 

 though it is fairly similar to Ceratopliina. It differs from this genus 

 in that it lacks tentacles and the ductus vaginalis opens separately 

 instead of looping back into the vagina. Altogether it has seemed 

 best to create a new genus for the species. 



Family HOPLOPLANIDAE Stummer-Traunfels, 1933 



Definition. — Schematommata of oval form, usually with tentacles; 

 penis consists of a stylet fastened directly to the prostatic vesicle; 

 true seminal vesicle absent; instead there are strongly developed 

 accessory seminal vesicles; no Lang's vesicle. 



Genus HOPLOPLANA Laidlaw, 1902 



Defmition. — With the characters of the family. 



HOPLOPLANA INQUILINA (Wheeler 1894) 



Planocera inquilina Wheeleb, 1894, p. 196, fig. 1. 



Hoploplana inquilina Bock, 1913, p. 228. — Hyman, 1939a, p. 145, figs. 12, 13. 



Material. — Two whole mounts and two sets of serial sections in 

 Pearse collection. 



Farm. — Oval, flat, 6 mm. long by 4 mm. wide, with pointed conical 

 tentacles (see figure in Wheeler, 1894, p. 197). 



Eyes. — Cluster of tentacular eyes in and around tentacle bases of 

 about 15 eyes each; loose cerebral clusters of 6-10 eyes extending 

 forward from the brain. 



Color. — Pale, translucent, with a reticulum of granules white by 

 reflected, black by transmitted light. 



Digestive tract. — Pharynx central, broadly oval, ruffled, with wide 

 ruffled folds; intestinal branches radiating to periphery with small 

 lateral branches, not anastomosed. 



Reproduotive system. — Described by Wheeler (1894), some points 

 added by Hyman, 1939a (figs. 12, 13, p. 145). What Wheeler called 

 the penis is the prostatic vesicle, to which the small pointed penis 

 stylet is directly fastened ; prostatic vesicle spherical with thick mus- 

 cular wall and small glandular center. Vasa deferentia greatly 

 expanded with thick muscular walls, serving as accessory seminal 

 vesicles; common ejaculatory duct formed by their union penetrates 

 prostate to base of penis stylet. 



Distrihution. — Recorded only from Woods Hole, Mass. 



Habits. — Sluggish, creeping slowly, commensal in the mantle cav- 

 ity of the snail Busy con. 



