214 CALIFORNIA ACADEMY OF SCIENCES. 



B. GABBi Crosse & Fischer, 1872. The description 

 given by the authors of this name is very full, and shows 

 that in size and form it is much like B. xantusi, having 

 nearly the same dimensions as Binney's figure, viz.: 



SHELL, MILLIMETERS. APERTURE, MILLIMETERS. 



B. gabbi 20i long, 1 1 wide B. gabbi 11 long, 7 wide 



B.xiintusi -21 " 11 " B. xantnsi 10 " " 



The chief differences are in color, described as " pale 

 brownish flesh-color,"" and in sculpture, which, with the 

 usual vertical riblets on the first i% whorls, has the rest 

 strongly marked by longitudinal striae crossing the lines 

 of growth, " subgranulately impressed at the crossing,'" 

 aperture a dull fleshy white, otherwise as in B. xanlitsi. 

 Binney"s mention of minute revolving fines in the types 

 shows that, as in B. insccndens, it varies, and like that 

 species may have them much stronger in local forms. 

 B. gabbi was only referred to " Lower California,"' and 

 is not mentioned in any of Gabb's own writings, but was 

 no doubt described from fresh specimens collected by 

 Gabb on the eastern side of the peninsula. As Binney 

 described bleached specimens of B. xantnsi, the resem- 

 blance was not very noticeable at the time. The authors 

 call B. gabbi somewhat intermediate between B.pallidior 

 and B. froteus, but the only way this can apply is in the 

 sculpture being like that of the latter, which is sometimes 

 found in B. iiiscendcns, and may be expected in local 

 varieties of others. As to possible hybrids of other 

 species, see remarks under each. Whether these are 

 really hybrids or only variations caused by local influ- 

 ences is a question not yet ripe for decision. I am in- 

 clined to consider B. gabbi the living and unworn state 

 of B. xaiitiisi, collected during the wet season, the latter 

 being known only in a damaged state. 



