308 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 85 



KEY TO THE SUBSPECIES OF CHONDROTHYRELLA (PLICATHYRELLA) ASSIMILIS 



Early postnuclear whorls distantly ribbed. 



Surface of shell exceedingly rough abronensis 



Surface of shell not exceedingly rough. 

 Peristome radially rayed. 



Spiral cords in the umbilicus very strong maceoi 



Spiral cords in the umbilicus not very strong signata 



Peristome not radially rayed. 



Spiral threads about the umbilicus rather distantly 



spaced assimilis 



Spiral threads about the umbilicus closely spaced. 



Spiral threads about the umbilicus very strong cisnerosi 



Spiral threads about the umbilicus not very strong— g-uirensis 

 Early postnuclear whorls closely ribbed gemma 



FIGUBE 98. — Distribution of the subspecies of Chondrothyrella (PUcathyreUa) assimilis: 

 (1) cisnerosi; (2) abronensis; (3) maceoi; (4) assimilis; (5) signataj (6) gemma/ 

 (7) jruireiwis. 



CHONDROTHYRELLA (PLICATHYRELLA) ASSIMILIS ABRONENSIS, new subspecies 



Plate 25, Figube 5 



This race comes from El Abron, Sierra de Limones. The junctions 

 of the sublamellar axial ribs and spiral threads form very strong 

 cusps, which give to this subspecies a rasplike surface. The peristome 

 is radially rayed with brown and the early postnuclear whorls are 

 distantly ribbed. 



The type, U.S.N.M. no. 492732, a complete specimen, has 6 whorls 

 and measures: Length, 13.0 mm; greater diameter, 10.2 mm; lesser 

 diameter, 6.8 mm. 



