1888.] NATURAL SCIENCES OF PHILADELPHIA. 291 



ed ; the base concave around the umbilicus, and the general asjiect 

 that of Patula. 



The jaw is like that of cimimfirvicda. 



The radula (2:»1. xvii, fig. d) is similar to that of hermndensis except 

 in the following points : the cusps are larger, with much more widely 

 reflexed cutting points ; the perfect lateral teeth are seven on either 

 side ; the change to marginals is quite abrupt, as there are but two 

 real transition teeth ; the marginals number about sixteen on each 

 side, the inner six or seven of about equal size, the outer ones rapidly 

 •decreasing toward the edge. The basal plates are longer than in the 

 other species. A central tooth witli two adjacent laterals and one 

 marginal are shown in the figure. 

 Poecilozonites circumfirmatus RedMeld. ({il. xvii, figs. r). 



A form with much the appearance of Hxjalosagda, a group with 

 which it has been classed by some authors. It is a delicate subtranslu- 

 •cent yellowish l)i-own shell, marked with brown streaks, spots and 

 flammules ; the whorls are separated by moderately impressed sut- 

 ures ; the apex is like that of reinicma ; the last whorl is more or less 

 angulate around the periphery, rather flattened below the angle, then 

 convex, indented around the narrow deeply perforating umbilicus ; 

 there is a white calcareous deposit around the columella, inside, as 

 in the other species, and an acute white lamella which revolves 

 within the base near to the periphery, a character which none of the 

 preceding species possess. The variation in form is very great — spec- 

 imens more elevated than my figure v being nut infrequent, and 

 these are connected by examples more and more depressed (fig. g) 

 -with the flattened lenticular form called by Pfeiffer H. discrepaus. 

 This extremely depressed variety, now figured for the first time, (PI. 

 xvii, fig. H.) cannot be considered specifically distinct from the P. 

 circumfirmata. 



Jaw (pi xvii, fig. b) transparent, very thin, arcuate, with blunt 

 ■extremities and a wide obtuse median projection below. 



Radula (pi. xvii, fig. a) as described for P. bermudensis, but with 

 only seven laterals, two or three transition teeth, and about twenty- 

 eight marginals. The marginals have longer basal plates than in P. 

 bermiidensis. 



