Long diameter seven eighths of an inch ; short diameter not quite 

 half an inch ; height one fifth of an inch. 



Inhabits La Paz, Gulf of California. Lieut. Green. 



It has the form of S. haliotoideus, and is nearly as smooth as 

 levigatus. It is about the size of S. planus^ and has the compressed 

 form of S. depressus. Its honey-yellow color is peculiar. 



NARICA OVOIDEA (PI. XIV. Fig. 10.) 



T. ovoidea, solida, albida, costis planulatis politis*ad 11 cincta, interspatiis 

 duplo angustioribus concinne clathratis ; spira acuta, anfr. 4, superne tabulatis, 

 ultimo magno, ovato : apertura ovata ; labro crenulato ; columella tenui, an- 

 trorsum concava, plica mediana instructa ; umbilico conspicuo, profundo. 



Shell ovoid, solid, dingy white, surrounded with well marked 

 grooves and square shining ribs, about eleven on the large whorl 

 and five on the others, the grooves about half the width of the ribs, 

 and delicately clathrate with longitudinal bars ; spire acute, whorls 

 four, shouldered above, the last whorl composing the greater part of 

 the shell. Aperture half the length of the shell, ovate, ribs render- 

 ing the outer lip crenate ; inner lip rather sharp, concave in front, 

 slightly attached to the whorl above and having a delicate fold at 

 the middle. Umbilicus well marked and deep. 



Length seven twentieths of an inch ; breadth three twentieths of 

 an inch. 



Purchased at Mazatlan. Col. Jewett. 



This curious shell it is difficult to classify ; perhaps there is no 

 genus now defined which can properly receive it. Littorina(?) 

 angistoma and excavata C. B. Adams, seem to belong to the same 

 group. 



TEREBRA ARGUTA (PL XIV. Fig. 19.) 



T. parva, acicularis, nitida, plicis longitudinalibus rectis acutis ad 10 ornata, 

 interspatiis concavis ; albida prope suturam fusco zonata, et intcrdum lineis 

 flexuosis picta ; apertura angusta, lunaris ; anfr. 8 planulatis, ultimo ad basim 

 spiraliter striato. 



Shell small, acicular, very acute and slender, glistening, com- 

 posed of about eight flattened whorls, having on each about ten 

 acute longitudinal folds, the spaces between fluted ; a few spiral 

 lines around the base of the last whorl ; aperture narrow lunate, 



