Jrom the Gulf of California, etc. 377 
obtuse radiating ridges along the dorsal slope at each end: color 
straw yellow, or cinnamon brown. 
Length 4 inch; height +4; inch ; breadth +, inch. 
On kelp or stems of Zoophytes, Santa Barbara. Col. Jewett. 
This curious little shell can be compared with no other species, 
unless it be A. alveus, which is still comparatively much broader. 
It has much the size and shape of a glume of wheat. 
CREPIDULA EXPLANATA (Pl XIV. Fig.7.) 
T. unguiformis, elongata, calcarea, apice terminali; antice angustata, trun- 
cata, denticulo mediano armata: marginibus ex lamellis disjunctis alveolatis ; 
dorso concavo; intus porcellana, lateribus incurvatis; septum dimidiam long. 
teste metiens, valdé arcuatum, margine concavo. 
Shell unguiform, long and gradually narrowing, incurved, apex 
acute, terminal and median; tip truncate, with a denticle at the 
middle ; sides apparently having a portion clipped off, presenting 
the edges of the lamellz of growth which have been separated 
from each other so as to give a cancellate appearance ; the edges are 
thus thickened and raised, so that the back of the shell is a concave 
trough. Exterior, dead white. Interior, polished porcelain white, 
the edges very slightly incurved, scarcely forming a cavity. Sep- 
tum extending nearly half the length of the shell, remarkably 
arched, its free edge slightly concave. 
Length 1} inch; breadth 4 inch; height 4 inch. 
Inhabits Monterey. Lieut. Green. Lower California. Maj. 
Rich. 
À very curious shell, which, from its structure, must have resided 
in tubes of some sort, perhaps those made by Pholas. Its most 
remarkable characters are the loose and cancellate structure of its 
edges, the truncate and dentate tip, and the excavated back as if 
made by a gouge. 
BULLA (AKERA) CULCITELLA (PI. XIV. Fig. 8.) 
= subcylindracea, solidula, albida, spiraliter concinne striata, — 
"Uia induta; anfr, quinque, ultimo elongato subfusiformi, antic i pans 
dato, supernis Spiram conicam efformantibus; sutura pro und? Nee ata: 
apertura linearis, antrorsum dilatata ; col lla valde co a, uniplicata ; 
Posti? sensim recedente. 
JOURNAL B. s. N. H. 49 OCTOBER, 1852. 
