346 Migliels' Descriptions of 



elevated, approximate, pointed and eroded ; kmule narrow, 

 lanceolate, and rather superficial ; external surface slightly 

 undulating, occasioned by the incremental strise, which under 

 a magnifier appear to be interrupted and rather coarse ; the 

 epidermis is of a dark, yellowish brown color ; the interior is 

 smooth, of a dark brown, inclining to a chocolate color; the 

 hinge margin is tiiin, the posterior side of the left valve is 

 sharp, which fits into a slight groove in the opposite valve, a 

 short distance behind the beak ; there is one cardinal tooth 

 in the right valve which is received into a subtriangular 

 space between two unequal teeth in the left valve ; muscu- 

 lar impressions superficial, reniform ; margins simple. 



Length |, height ^^g, breadth \ inch. 



Habitat. Casco Bay. 



Remarks. I have obtained only a single specimen of this 

 species ; this I found in the stomach of a haddock, in 1842. It 

 is readily distinguished from all the other species of the genus 

 by its extraordinary obliquity, and by the livid color of the 

 interior. 



Bulla pertenuis. 



B. testA minutci, cylindracea, albida, liyalinti ; anfiactibus quatuor j spirS. 

 elevatd ; labro supernc recto, infrcl rotundato ; apertura superne augustata, 

 infra lat^i. 



Plate XVI. Fig. 3. 



Shell very small, cylindrical, of a dingy white color, very 

 thin and fragile ; whorls four, rounded, all lying in the snme 

 plane; suture distinct, as seen under the microscope; spire 

 elevated ; labrum nearly straight at the posterior part, rounded 

 anteriorly, returning into the shell it forms a delicate, slightly 

 elevated lamina, which, under the microscope, is seen to oc- 

 cupy nearly the whole length of the columellar region ; aper- 

 ture very narrow posteriorly, broad and rounded anteriorly. 



Length ^^g inches, breadth j^g inches. 



Habitat. Casco Bay. 



Remarks. When greatly magnified this shell resembles 

 B. Gouldii, Couth, but besides being much smaller, it is pro- 



