340 BULLA. 



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. 

 {Ball). 



Blake Station 43, 339 fms. 



Bulla f eburnea 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 Bulla eburnea 

 of A. Adams, Avhich is a member of the genus Volvula. 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. (Dall). 



Species of the w^est coast Of America. 



B. (40ULDIANA Pilsbry. PI. 36, figs. 22, 23, 24. 



Shell large, ovate or oval, thin ; pinkish fawn-colored dappled 

 with slate-black spots, each shading into the ground-color on the right 

 and bordered ivith 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 stride, or but a few in its depth. Col- 

 umella thickened with a crescentic callus. Interior oj 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 Cape St. 

 Lucas ; Guaymas, West Mexico and Mazatlan. 



V Bulla nebulosa Gould, A. Ad., Thes. Conch, ii, p. 578, pi. 123, f. 



79^ 80.— Mke., Zeitschr. f. Mai. 1850, p. 162.— Carpenter, Moll. 

 Western N. A, pp. 22, 26, 79, 85, 107, 132, 151, 153 ; Rep. Brit. 

 Asso. Adv. Sci. 1856, pp. 198, 233, 234, 237, 284, 289, 313, 352, 

 353 ; Mazatlan Catal., p. 173, 540 ; P. Z. S. 1856, p. 220.— Sowb.^ 



