132 PROCEEDINGS OF THE NATIONAL. MUSEUM Vol.89 



combinations of these characters, which easily fall into four categories 

 here recognized as subfamilies. 



The first of these subfamilies, the Chondropominae, has a simple 

 chondroid plate consisting of a number of whorls, which usuallj^ have 

 more or less of a finely granular calcareous deposit on the outside. 

 In the second, the Rhytidopominae, the whorls bear a calcareous 

 desposit, which may consist of simple, retractively curved riblets 

 that may remain distinct or may become fused at the edge into a 

 solid plate. In the third, the Adamsiellinae, which is poorly repre- 

 sented in Cuba, the upturned outer edge of the preceding whorl is 

 strengthened and built into a strongly elevated lamella by the inner 

 edge of the succeeding turn. This lamella has no ribbing or buttress- 

 ing. In the fourth subfamily, the Annulariinae, the whorls of the 

 operculum are provided with a strong calcified lamella, which rises 

 from the inner edge of the turns; it may be vertically placed or re- 

 flected to parallel the basal plate, and it may be smooth or ribbed. 

 It is usually connected with the basal plate by reenforcement. 



The presence or absence of breathing devices of definite type is not 

 restricted to any of the subfamilies; they find service in all of them. 

 These breathing devices vary from a mere notch near the posterior 

 angle of the aperture to a puncture in the parietal wall, which punc- 

 ture may be further emphasized by having a siphon built on the out- 

 side of it. This siphon even may be prolonged and deflected tlii'ough 

 the suture to the umbilicus, which it closes, and breathing is thus 

 effected through the hollow axis of the shell and through the decol- 

 lated apex. Or, the columellar wall may have a slit at some distance 

 from the peristome, through which breathing communication is estab- 

 lished with the hollow axis. 



Another feature, the taxonomic value of which we have not defi- 

 nitely decided upon in this work, is the nuclear sculpture. The 

 embryonic whorls, usually about two, are microscopically granulose, 

 that is, smooth under hand-lens magnification. In two groups, 

 Limadora and Limadorex, they bear strong definite sculp tm-e; in the 

 first this is thimble pitting, and in the second thimble pitting and 

 spiral threads and axial ribs. In the rest of the shell characters they 

 are not unlike other groups, but in these embryonic features they are 

 widely at variance with the other members of the family. 



The three subfamilies here discussed confirm our findings in the 

 Chondropominae: that Cuba represents three centers of develop- 

 ment, namely, an eastern, a central, and a western province. 



Where we have referred in the keys to closely spaced or axial 

 riblets, the statement refers to the later whorls. 



We have used brackets around certain names to indicate that the 

 original describer gave credit for the species to the one whose name 

 appears in brackets, for example ([Gundlach] Pfeiffer). 



