VROCOPTID MOLL VSKS—BA R TSCH. 



115 



pinched immediately anterior to the periphery, which renders this 

 area slightl}' concave; the rest of the base well rounded and marked 

 by the riblets, which are rendered somewhat sinuous in passing over 

 the peripher}^ and the depressed area. Aperture not entirely com- 

 pleted in our specimen, showing- the almost obsolete fold. Internal 

 pillar thin in the last whorl, graduall}" increasing in diameter to 2.3 

 mm. in the third to last volution, diminishing from there to the decol- 

 lated apex. The pillar has a spiral twist running throughout the spire 

 a little posterior to the middle, and a spiral lamella, which is inserted 

 on the columella, a little above the floor. This fold is 

 almost obsolete in the last whorl, growing gradually 

 stronger posteriorly. It attains its 

 maximum development in the antipe- 

 ludtimate volution, where it extends 

 almost one-third of the way across the 

 inside of the whorl; from this point it 

 gradually diminishes in size and disap- 

 pears altogether in the sixth to last 

 volution. In the third and fourth to 

 last volution the lamella is incised at 

 regular intervals b}' slits, which extend 

 about one-sixth of the way from the 

 edge to the insertion of the columella. 

 The type and only specimen, Cat. No. 

 58055, U.S.N.M., was obtained from 

 Mr. Bland by Dr. Stearns, and is said to 

 come from near Mazatlan. It has 9.1 

 which measure: Length, 33.7 nmi.; diameter of penultimate 



Fig. 3.— Interior 

 VIEW OF Anisos- 

 PIRA BLANDI. 



Fig. 4.— Detail of 



PILLAR of ANI- 

 SOSPIRA BLANDI. 



whorl 



diameter of 



whorl, 11.5 nnu. ; diameter of fifth to last whorl, 12 mm. 

 first whorl, 6.1 mm. 



The present species is a somewhat puzzling form; the puncture at 

 the decollated apex and inflated pillar would place it in Cocloeeiitruin., 

 but the peculiar sculpture of the lamella allies it closely to Anisospira 

 (Dissotropis) stearnsi. 



CCELOCENTRUM NELSOTH Dall. 



There are two lots of this species in the collection, the type. Cat. 

 No. 10736S, U.S.N. M., and four other specimens. Cat. No. lcS5902, 

 U.S.N.M., collected by E. \V. Nelson and E. A. Goldman, respectively, 

 at Tuxtla Gutierrez, Chiapas, Mexico. 



