obtuse radiating ridges along the dorsal slope at each end : color 

 straw yellow, or cinnamon brown. 



Length % inch ; height y 1 ^ 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 (PI. XIV. Fig. 7.) 



T. unguiformis, elongata, calcarea, apice terminal! ; antice angustata, trun- 

 cata, denticulo mediano armata ; marginibus ex lamellis disjunctis alveolatis ; 

 dorso concavo ; intus porcellana, lateribus incurvatis ; septum dimidiam long. 

 testae metiens, valde 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 lamellae 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 inch ; height inch. 



Inhabits Monterey. Lieut. Green. Lower California. Maj. 

 Rich. 



A 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. 



BULL A (AKERA) CULCITELLA (PL XIV. Fig. 8.) 



T. sttbcylindracea, solkhila, albida, spiraliter concinn striata, epidermide 

 stramineo induta ; anfr. quinque, ultimo elongato subfusiformi, antice rotun- 

 dato, supernis spiram conicam efformantibus ; sutura profunde canaliculata : 

 apertura linearis, antrorsum dilatata ; columella valde contorta, uniplicata ; labro 

 postice sensim recedente. 



