220 BULLIDyE. 



and at the umbilical region it enters the shell and forms a conspicuous fold. Length, 

 seven fortieths of an inch ; breadth, four fortieths of an inch. 



Found on Chelsea Beach by myself, at Provincetown by Colonel Totten, at New Bed- 

 ford by Professor Adams, and is not unfrequently taken from fishes. 



The same remarks which were made under the preceding species, as to its generic 

 place, apply to this species. 



This shell closely resembles the figures, and agrees in general with the description, of 

 Bulla obtusa, of Montagu ; but in neither of them is any lold at the base of the pillar 

 noted, and our shell has a more elevated spire, and wants the conspicuous lines of growth 

 which peculiarly mark the British shell. B. cannlicukita differs in its more slender, cylin- 

 drical, and smooth appearance, the broad and shallow groove of the whorls, its very acute 

 summit, and its more slightly plaiied pillar-lip. In adult specimens it is easy to discrim- 

 inate the two species ; but the half-grown specimens are so nearly alike as to render it 

 almost impossible to separate them. Mr. Lea describes and figures a fossil species iu his 

 " Contributions to Geology " under the name of Actaon WetherilU, which must very 

 closely agree with this shell. 



Oemis CYLICHWTA, Loven. 1846. 



Tentacular lobes connate, indistinct; eyes sessile on their front 

 bases. Mantle with a thick, posterior lobe, partially closing the 

 aperture of the shell. 



Shell solid, cylindrical, involute ; s])ire none, apex obtuse, umbil- 

 icated ; aperture luxrrow and linear, as long as the body whorl ; in- 

 ner lip callous, with a single anterior fold ; outer lip straight, simple. 



Cylichna alba. 



Fig. 98. 



Shell cylindrical, smooth, whitish, of the size of a grain of rice, a pit in place 

 of the spire. 



Volvaria alba, Brown, Conch, iii. 3. 



Bulla triticea, Couthouy, Bost. Journ. Nat. Hist. ii. 88, pi. 2, fig. 8 (18.18); Sillim. 



Journ. Old Series, xxxiv. 217 (1838). — Gould, Liv. 1G.5, fig. 98. — Ue Kay, N. Y. 



Moll. 17, pi. .3.5, fig. 326. 

 Bulla corticafa, Moller, Ind. Gr. 6. 

 Cylichna alba, Stimpson, Check Lists, 4. 



Shell cylindrical, polished, rather solid, of a dull white color, and 

 covered with a thin, rusty epidermis ; marks of growth very del- 

 icate, and numerous minute revolving lines may l)e seen un- 

 der a magnifier ; a circular ])it occupies the region of the 

 s})ire, from the margin of which the outer lip takes its origin, i 

 and, rising a little, passes forward in a direction nearly paral-i 

 L.atba. 1^^ ^^^ ^^^^ j^|.^ margin of the shell, forming a long, narrow, 

 aperture, which suddenly becomes double this breadth, near the 



