340 BDLLA. 



body within the aperture. Lon. of shell and aperture, 7*25. Max. 

 lat. of shell, 4'25 ; of aperture, 2'0; mill. lat. of aperture, 0'75 mill. 

 (Da//)- 



Wake Station 43, 339 fins. 



f ebnrnea DALL, Bull. M. C. Z. ix, p. 98, 1881 ; Blake 

 Rep. p. 55, pi. 17, f. 6. ? Diaphana gemma VERRILL Amer. Journ. 

 Sci. (3) xx, p. 399. 



I have seen only one specimen of each of the above species, and 

 they certainly appear very different in some respects ; but the range 

 of variation in these forms is little understood, and I do not feel con- 

 fident that it may not be larger than generally supposed. In that 

 case it is possible that the two forms may represent the extremes of 

 one species. This should not be confounded with the Sulla eburnt " 

 of A. Adams, which is a member of the genus Volvnla. Not possess- 

 ing the soft parts, I have preferred to refer this species to the genus 

 Bulla, though it may belong in the preceding family. (DaU). 



SPECIES OF THE WEST COAST OF AMERICA. 



B. douLDiANA Pilsbry. PI. 36, figs. 22, 23, 24. 



Shell. large, ovate or oval, thin; pinkish fawn-colo-red dapj>ll 

 with slate-black spots, each shading into the (/round-color on the r if/ Jit 

 and bordered with whitish on the left, or with similarly shaded 

 ^.-shaped or $> -shaped markings; covered when fresh by a yellow- 

 ish-brown or mahogony epidermis. Surface smoothish, with irregular 

 growth-wrinkles; showing under a strong lens an extremely minute 

 granulation. Apex narrowly umbilicated, the interior of the per- 

 foration showing no spiral strife, or but a few in its depth. Col- 

 umella thickened with a crescentic callus. Interior of mouth show- 

 ing the external markings viewed by reflected light. 



Alt. 55, diam. 37 mill. 



Alt. 40, diam. 30 mill. 



San Pedro, Santa Barbara and San Diego, California, to (_\i^>e St. 

 Lucas ; Guaymas, West J/ir.nVo and Mazatlan. 



ll'illa nebulosa Gould, A. AD., Thi-s. ( '..m-h. ii, p. 578, pi. 12.". f. 

 79, 80. MKK., Zeitschr. f. Mai. 1850, p. 162. CA IM-KN n.i:. Moll. 

 Western N. A, pp. 22, 26, 79, 85, 107, 132, 151, L58; Hop. Brit. 

 Asso. Adv. Sci. 1856, pp. 198, 233, 234, 237, 284, 289, 313, 



; Mazatlan Catal., ]. 17.", 540 : P. /. S. 185P,, p. 220. Sown., 



