200 THE BERMUDA ISLANDS. 



ceding species possess. The variation in form is very great — 

 specimens more elevated than my figure f being not infrequent, 

 and these are connected by examples more and more depressed 

 (fig. g) with the flattened lenticular form called by PfeifFer H. 

 discrepans. This extremely depressed variety, now figured for 

 the first time (PI. 16, fig. h.), cannot be considered specifically 

 distinct from the P. circumfirmatus. 



Jaw (PL 16, fig. b) transparent, very thin, arcuate, with blunt 

 extremities and a wide obtuse median projection below. 



Radula (PI. 16, 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. Bermudensis. 



Helix (MicTophysa) hypolepta Shattleworth. 



Of this minute form no diagnoses or figures have been pub- 

 lished, although the name has been upon the lists for many 

 years. The shell was apparently unknown to Pfeiffer except 

 by the remarks of Shuttleworth, who saj's under his diagnosis 

 of II. minuscula Binn. : " Altera species proxima, sed testa 

 aperte umbilicata, et anfr. ultimo basi devio distincta,in insula 

 Bermuda occurrit, cujus specimina plurima ab am. Bland ac- 

 cepi, atque H. hypolepta nominavi." 



The shell is minute, discoidal, whitish, subtranslucent and 

 shining, with wrinkles of increment above, nearl}' smooth be- 

 neath. The four whorls are very convex, quite gradually 

 widening, the last one with the periphery above its middle, 

 the lower lateral surfaces sloping somewhat as in H. vortex Pfr. 

 The aperture is small, not very oblique, oval. The lip is acute, 

 upper and basal margins quite arcuate, the baso-columellar 

 margin slightly expanded. The umbilicus is broad, more than 

 one-third the diameter of the shell. 



Alt. 1, diam. 2J mill. 



It is evidently allied to H. (Microphysa) vortex Pfr., but is 

 much smaller, flatter, with broader umbilicus. I need not 

 compare Zonites minusculiis-wiih this shell ; a glance at the fig- 

 ures will show at once the difference. 



