152 BULLETIN 192, UNITED STATES NATIONAL MUSEUM 



ABBOTTEI.I.A GABBI (Crosse) 



Shell small, helicoid, marked by closely spaced axial ribs, which are 

 gathered into groups producing a crenulated effect at the periphery. The 

 spiral sculpture consists of cords, which vary very materially in strength ; 

 some are slender, others form strong keels. Suture channeled. Periphery 

 keeled. Base well rounded and marked by spiral cords, which again vary 

 in strength ; this is also the case of the spiral cords on the umbilical wall. 

 The axial riblets extend over both base and umbilical wall. The umbilicus 

 is broadly funnel-shaped. Aperture circular ; peristome double, the inner 

 slightly exserted ; the outer broadly flaringly expanded and rayed. Oper- 

 culum with central nucleus and an almost vertical lamella. 



ABBOfTELiL-A GABBI GABBI (Crosse) 



Plate 26, Figures 5-7 



1873. Choanopoma gabbi Crosse, Journ. Conchyl., vol. 21, p. 353. 



1874. Choanopoma gabbi Crosse, Journ. Conchyl., vol. 22, p. 84, pi. 3, fig. 2. 

 1920. Choanopoma gabbi Henderson and Bartsch, Proc. U. S. Nat. Mus., vol. 



58, p. 75. 

 1933. Choanopoma gabbi Pilsbrv, Proc. Acad. Nat. Sci. Philadelphia, vol. 85, 

 pp. 129-130, pi. 7, figs. 5, 5a, 6. 



This subspecies has been restricted by Dr. H. A. Pilsbry, who had 

 specimens from the Gabb collection which embraced both this and Abot- 

 tella crossei. 



Dr. Pilsbry was good enough to give us one of the specimens from 

 the Gabb collection, which I am describing and figuring. Gabb's specimen 

 bears merely the label "Santo Domingo," and I have seen nothing to 

 enable me to fix the locality definitely. 



U.S.N.M. No. 504098 has 4.6 whorls, the last of which bears 30 of 

 the knobs consisting of fused axial riblets at the periphery and 192 fine 

 riblets. It has seven spiral threads between the summit and the periph- 

 ery, two on the base, and three within the umbilicus, and measures: 

 Height, 3.7 mm. ; greater diameter, 6.6 mm. ; lesser diameter, 5.2 mm. 

 Aside from the lesser number of ribs and lesser number of spiral cords, 

 the shell is also much smaller than the one I am calling Ahhottella gabbi 

 pilsbryi; the shell is much more acutely sloping between the periphery 

 and the first strong spiral cord, which gives the last whorl a decidedly 

 more angulated aspect. 



ABBOTTEl,I.,A G.ABBI PII.SBBYI, new subspecies 



Plate 27, Figures 7-9 



This race was collected by Dr. W, L. Abbott in a cave on the Rio Seco 

 near Samana, Samana Bay, Dominican Republic. 



The type (U.S.N.M. No. 504099) has 4.6 whorls and 42 fused knobs 

 and ribs at the periphery and 208 fine axial riblets. It has seven spiral 

 threads between the summit and the periphery, five on the base, and 



