80 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 58. 



The group of Diplopoma architectonicum: 



Diplopoma architectonicum (Gundlach) Pfeiffer Eastern Cuba. 



Dijilopoma torrei Ramsden Eastern Cuba. 



Subgenus JAMAICIAC. B. Adams. 

 1850. Jamaicia C. B. Adams, Contrib. Conch., p. 88. 



Shell almost turbinate, marked by strong axial riblets and spiral 

 threads. Operculum convex, the reflected lamellae marked by strong 

 retractively slanting riblets. 



Type oftJie subgenus. — Cyelostoma anomala C. B. Adams. 



The tj-pe species is the only one kno^vn of tliis gi-oup at present 

 It comes from Jamaica. 



The descriptions of the following species are necessary in order to 

 give status to the groups which the}^ represent and which are referred 

 to in the preceding pages. 



PARACHONDRIA (PARACHONDRIA) GONAVICOLA, new species. 



Shell elongate-ovate, ashy gray. Early whorls decollated. The 

 three and a half remaining in the type are well rounded and crossed 

 by numerous slender, retractively slanting, axial riblets, which are 

 decidedly crowded on the last turn. These riblets are gathered 

 together as tufts at the summit of the whorls, and render the suture 

 denticulate. The spiral sculpture consists of numerous slender low 

 rounded threads, which render the axial riblets wavy and very 

 slightly nodulose. Periphery of the last whorl well rounded. Base 

 somewhat inflated, well rounded, narrovdy umbilicated, marked like 

 the spire, excepting the umbilicus, in which the spiral sculpture is 

 intensified. The last whorl is solute for an eighth of a turn. Aper- 

 ture ovate; posterior angle acute, continuing backward as a nodulose 

 keel to where the whorl becomes appressed to the preceding turn. 

 Peristome not expanded but somewhat thickened. Operculum 

 typicalh^ Parachondroid. 



Ty2)e. — Cat. No. 314944, U. S. N. M., and thirty-three specimens, 

 were collected by Dr. W. L. Abbott on Gonave Island, Haiti. The 

 type measures: Length, 15.4 mm.; greater diameter, 10.4 mm.; 

 lesser diameter, 9 nam.; length of aperture, 7.1 mm.; diameter of 

 aperture, 5.2 mm. 



This species is related to Parachondria (Parachondria) dentilobata, 

 Weinland, but is uniformly much smaller than that species. 



TORRELLA (TORRELLISCA) SIMPSONI, new species. 



The shell is elongate-conic, decollated, leaving four and a quarter 

 well rounded whorls, the last being solute for a short distance, and 

 obtusely carinated along its posterior angle. The shell is narrowly 

 umbilicated and open at the truncated apex, leaving a hollow axis. 



