MUSEUM OF COMPARATIVE ZOOLOGY. 285 



(Sandalium) aculeata Gmelin and C. adunca Sowerby, all of which agree very 

 fairly in general characters. The foot is rather small, with a thin front edge ; 

 the neck and muzzle are long, thin, narrow, and vertically compressed, with 

 short stout tentacles, with the eyes about midway from their outer bases 

 toward the tips ; behind the right tentacle, and just above the epipodial line, 

 is the slender cylindrical verge, in the male ; this organ is sometimes as long 

 as the tentacle, sometimes only half as long, but always more slender. On each 

 side of the neck is a broad thin lamina, extending back to the junction of the 

 neck and foot. This is epipodial in origin, and usually flat or slightly puck- 

 ered by the alcohol. When the eggs are deposited, tbey appear in irregular 

 groups, enclosed in pedunculated gelatinous masses (Crepidula adunca), or in 

 a single large gelatinous mass. At this time the epipodial lamina on each side 

 becomes enlarged, puffed up like a hood or dome, between its outer margin 

 and the neck, while the corners of the foot project, each in a large thin lingui- 

 form flat process. The inner edges of these processes overlap, and form a floor, 

 which is roofed in by the neck with its exaggerated lateral pouches on each 

 side. In this shelter the egg masses are protected (C. adunca) until the young 

 are hatched. There is some variation of details in different species, but in 

 general the process is about the same, at least in all I have examined. 



The gills in this family are much more like Pelecypod gills than are those 

 of most Gastropods. The lamina? are long, almost filamentous, and sustained 

 by chitinous rods. Their tips are slightly enlarged and opaque whitish, while 

 the rest is translucent. The osphradium, like small short-laminated gill, is 

 situated by the side of the ctenidium. 



Section JANACUS Morch. 

 Crepidula protea Orbigny. 



Crepidula protea Orbigny, Moll. Cuba, II. 192, pi. xxiv. figs. 30-33, 1842 ; Dall, 

 Bull. M. C. Z., IX. p. 80, 1881. 



Habitat. Off Havana, at several stations, varying in depth from 80 to 450 

 fathoms. 



This is probably identical with C. unguiformis Lam. 



Section SANDALIUM Schumacher. 



In adopting the name Crepidula of Lamarck, Schumacher divided the group 

 into two genera, each of which contains two sections, in this manner : — 

 Genus X. Sandalium Schumacher. 



Section a, type Patella porcellana Lin. (= Crepidula s. s.) 



Section /3, type Patella aculeata Chemn. 

 Genus XL Trochita Schumacher. 



Section a, type Patella chinensis Lin. (= Cahjptrcea Lam., 1799). 



Section /3, type Patella trochiformis Gmel. 



