PUPILL^A-LUCAPINA. 181 



Moll., p. 62, t. 4, f. 11.— Sowb. Thes. iii, p. 204, f. 228, 229.— 

 Pwpillia apertura Gray. — Not F. aperta Reeve. 



This shell may be recognized by the peculiarity of the margin, 

 the inner layer projecting at the border beyond the outer, forming ■ 

 a narrow, white ledge. The sculpture of fine concentric striae over 

 radiating riblets, is shown in fig. 7 of pi. 44. I have been unable 

 to find the description of P. aperta in the appendix to Beechey's 

 Voyage. 



Krauss describes the animal thus : The animal has the size and 

 form of Onchidium peronii Cuv., is oval-elliptical, strongly convex, 

 spreading out near the margins, smooth, covered with a leathery 

 skin, whitish, perhaps also reddish-gray, with many unequal black 

 flecks. Above, a third part from the front, there is a small hole, 

 only 4 mill, long, in the depth of which, exactly as in Fissurella, 

 there is a thick membrane pierced by a round opening, which serves 

 as a gill-hole through the fissure in the shell. The shell is com- 

 pletely covered by the leathery skin, so that one must cut thi-ough 

 it to extract the shell. The head lies several lines within the ex- 

 panded front border of the mantle, and has two short tentacles, 

 scarcely reaching as far as the end of the snout. The mantle-mar- 

 gin is thin, and much broader than the wrinkled and granulated 

 foot. 



Genus LUCAPINA Gray, 1857. 



Lucapina Gray, Synops. Brit. Mus. 1840, p. 151 (no diagnosis or 

 species mentioned) ; Proc. Zool. Soc. Lond. 1847, p. 147 {Fissurella 

 aperta Sow. and Lucapina elegans Gray mentioned) ; Guide to the 

 Syst. Distrib. Moll. Brit. Mus., p. 166, 1857 (the genus for the first 

 time diagnosed, L. eancellata and L. crenulata mentioned). — Lu- 

 capina of P. P. Carpenter and American authors generally. Not 

 Lucapina H. & A. Adams, Genera Rec. Moll, i, p. 447, 1858. 



There seems to have been the greatest indecision in Gray's mind 

 as to which group of the Fissurellidna he would attach this name. 

 He finally decided on the West American species in 1857. It should 

 be noted that Lucapina of the brothers Adams is the same as 

 Glyphis Cpr. 



Shell large, oblong-oval, imbedded in the mantle, but large enough 

 to cover most of the upper surface of the animal ; apex a little in front 

 of the middle, entirely removed by the large oval perforation ; edges 

 of shell not thickened, very regularly and finely crenulated at all 



