292 rjiocEEDii^Gs oe the geological S0CIET3'. [Feb. 21, 



The spire of the single example has completely disappeared by 

 erosion, so that nothing but the last whorl is left, and even that 

 seems to have been somewhat encroached upon by the dissolving 

 properties of the water in which this mollusk lived. The shell is 

 different from that of any of the genus I know of inhabiting the West 

 Indies or South America. 



42. Dentalitjm dissimile, spec. nov. PI. XYII. fig. 4. 



Shell subpolygonal and striated at the apex, becoming gradually 

 round, smooth, and shining near the aperture, which is circular. 



43. Yeemetus paptjlosijs, spec. nov. PI. XYII. fig. 3. 



Shell nearly straight, rather irregularly spirally contorted, orna- 

 mented with regular longitudinal rows of tubercles interlined with 

 crenate striae ; aperture subcircular. 



44. Yenus paphia, Linn. 



Syst. I^Tat. p. 1129; Lamarck, An. s.vert. (ed.Desh.) vol.vi.p.371. 



45. Yenus Woodwaedt, spec. nov. PI. XYIII. fig. 1. 



Shell subtrigonal, somewhat inequilateral, anteriorly rounded, 

 posteriorly somewhat angulated ; ornamented with numerous fine 

 radiating costellae, interrupted by equidistant concentric crenulate 

 ridges, which are continued across the large lunule ; margin beneath 

 the lunule internally obsoletely toothed. 



A form allied to V. cancellata, Linn., abundant in the Caribean Sea. 



46. CrTHEREA (Callista) planivieta, spec. nov. PI. XYIII. fig. 3. 

 Shell inequilateral, transverse, oval, compressed ; valves polished, 



ornamented with numerous flat, slightly irregular, concentric ribs, 

 which are much closer than their interstices ; umbones prominent, 

 approximated ; lunule scarcely impressed. 



This bivalve approaches closely to C. erycina of the Eastern seas. 

 It is also allied to G. striatella of the Belgian Tertiaries, and even 

 more closely to C. erycinoides of the Bordeaux beds. 



47. Cytherea (Circe) carbasea, spec. nov. PI. XYIII. fig. 13. 



Shell rounded, rather inequilateral, tumid, sulcated by lines of 

 growth decussating with numerous radiating striae, which divaricate 

 on the anterior part of the disk, and become subrugose towards the 

 posterior margin ; lunule large, scarcely distinct ; posterior margin 

 rounded ; anterior margin somewhat produced. 



The character of the ornamentation in this species approaches to 

 that of C. divaricata, Chemn., and in general form it is related to 

 that species and to several others of the same group inhabiting both 

 the eastern and western seas, or found fossil in Tertiary formations. 



48. LuciisrA Pein^jststlvanica, Linn. 



Syst. Nat., p. 1134. 



This well-known species is also found fossil in the Miocene deposits 

 of Piedmont and of North America. 



