334 BULLA. 



umbilicus. Smaller than B. media, with narrower umbilicus, 



Senegambia. 



B. adansonii PH., Zeitschr. f. Mai. 1847, p. 121. A. AD., Thes. 

 p. 576, pi. 123, f. 13. SOWB., Conch. Icon., f. 13. DAUTZ., Mem. 

 Zool. Soc. France, iv, p. 25, 1891. 7)*. adansoniif var. minor DKR., 

 Ind. Moll. Guin. Infer, p. 4, pi. 4, f. 11, 12. 



Some specimens I have seen of this species differ from B. striuta 

 in the points mentioned by Philippi. The figure on pi. 38 is copied 

 from Reeve, and is larger than the shells before me. Dunker has 

 given two figures of a var. minor. See pi. 39, f. 74, 75. 



Specimens referable to B. adansoni are -also before me from 

 Corisco, W. Africa. They constantly possess basal grooves, but 

 there are none at the vertex. The apical umbilicus is nearly as 

 wide and open as in typical B. striata. The color-pattern is a close, 

 even speckling of white dots, each with a dark brown or blackish 

 dot at its left side, and there are two or three dark girdles. Alt. 

 24, diarn. 13 mill. One of these is shown in pi. 48, fig. 21. 



It is indeed difficult to distinguish some West African specimens 

 from the Antillean B. amygdala; but as the geographic ranges of 

 the two are now so widely sundered, I consider it best to make the 

 distinction between them here. The only alternative to this course 

 would be to " lump " the whole striata group. Perhaps mala- 

 cologists may eventually rank the various forms of this group as 

 " subspecies " or geographic varieties ; and this would be by no 

 means an unphilosophical procedure. 



VAR. COMPRESSA Rochebrune. PI. 39, figs. 66, 67. 



Shell distorted elongate, thick, longitudinally intensely striated, 

 concentrically, very minutely lirate at the anterior margin, line dis- 

 tant; vertex obtuse, profoundly umbilicate. Aperture subample, 

 pyriform, narrow in front, dilated behind [sic] ; lip equalling' the 

 spire; flattened in the middle, thickened and recurved below ; col- 

 umella arcuate thickened. 



Alt. 17,diam. 10 mill. (Rochebr.). 



Fossil hi the conglomerates of Santiago, Cape Verd'es. 



B. compressa ROCHEBR., Nouv. Arch, du Mus. (2), iv, p. 265, pL 

 18, f. 10. 



Closely allied to B. adansonii and var. minor Dkr. 



