l:i I I L 



th. 'in- -Iv.-- MIT moMly not tlmr<MiL r lily ditleimt iat< d into " -p ' 

 if l>y tluit term we understand isolated ;nd unconnected races. 

 Then- arc. however, geographically restricted forms which in their 

 average feature- constitute moderately tangible race.-; and ratherthan 

 lose sight of these iillereiices which are certainly correlated 



with geographic ran.ire, ue have herein recognized the conventional 

 41 species" based upon them. To >ome minds who hold the "species" 

 to he a sacred fetich, the course of the "lumper" would he more 

 acceptable ; and they may write all there is of the *friata group of 

 Bulla, under that name. It is simply a question of what degree or 

 grade of racial deviation is worth formal recognition in nomencla- 

 ture; and this must in the nature of things, remain a question of in- 

 dividual opinion. 



(Group of B. >7 //.- 



I'nder B. striatu the genesis of the various races of this group i.- 

 discussed. 



B. AMv.ii.ALA Dillwyn. 1M. :'8, figs. 49, 50, 62, 63, 64, 65 ; pi. 39, 

 fi. 79. 



. 



Shell oblong, somewhat cylindrical and narrower toward the 

 vertex, solid, heary <md xtrvmj, not very shining, clouded and mottled 

 indistinctly with purplish on a pale ground, more or less obvionn/n 

 spotted or blotched with deep purple or blue-bhick, the spot* ."had in if 

 into the ground color on the left side, whitith-margined u the right 

 side of each. Surface showing under the lens no microscopic spiral 

 xtriation (such as occurs in B. striata, uc>-i>h'nf<i/is and solida), but 

 having some spaced spin/I impi-r^-d ////>-.s toward the bam, and occa- 

 sionally a few near the vertex, but these are more often absent. 

 Vertex not especially compressed having a deep and rather large 

 apical umbilicus, which is more or less lirate within. Outer Up thirl-, 

 /irai'i/y calloused where it r we* from the certex ; its outer portion 

 straight, not convex; base broadly rounded. Columrlla arcuate. 

 with a eery heavy refle.n-d cn-wiiti'i* callus, the outer edge of which i* 

 well raised from the whorl throughout^ leaving a chink behind it: 

 parietal callus strong and white ; interi.tr lined with :i white callus. 

 Alt. 40, diam. 23 mill. Some adults are smaller, alt. LV, diarn. 15 

 mill., and others larger, alt. 46. diam. "11 mill. 



St. Thomax, Tortol'i. Cttracoo. and GMfoj r<iria (Robert S\\ii 

 West Indies generally. 



