198 LUCAPINEI.LA-LUCAPINA. 



L. limatula Reeve. PI. 36, fig. 13 ; pi. 61, figs. 6, 7, 8, 9. 



Shell small, oblong, narrower in front, rather depressed, the sub- 

 central summit occupied by the oblong fissure, of the same shape as 

 the shell, its length contained in that of the shell about 4 2 times. 

 Surface sculptured with alternately large and small radiating rib- 

 lets in front, but at the sides and posteriorly, three small riblets 

 occur between each pair of large ones, and of these three the middle 

 one is largest ; all this radiating striation is crossed by regular con- 

 centric laminae, a little over a half millimeter apart, rising into erect 

 semicircular scales wherever they intersect the radiating riblets. 

 Color white, unicolored or rayed with ashen or blackish. 



Inside white, showing the dark rays when they are present on the 

 outside ; callus rim of the perforation narrow. Muscle-impression 

 not impressed ; edges thickened at the sides, crenulated front and 

 back. 



Length 13, breadth 71, alt. 4 mill. 



Length 13, breadth 71, alt. 2'8 mill. 



Gape Fear ; Key West. Fla. ; St. Vincent and Barbadoes, West 

 Indies. 



Fissurella limatula Reeve, Conch. Icon. f. 115, Aug., 1850. — 

 Fissurellidea limatula Eve. Dall, Rep. on ' Blake ' Gastropoda, p. 

 409 ; Bull. U. S. Nat. Mus. no. 37, p. 170. 



Very similar to the Californian L. callomarginata, but lighter 

 colored and smaller. When adult the lateral margins of the shell 

 are thickened, as in callomarginata. 



* * 

 Genus LUCAPINA Gray. (See p. 181). 



Since the account of Lucapina was printed I have studied certain 

 species which I had formerly referred to G typhis; and have con- 

 cluded that the following West Indian forms should be placed under 

 Lucapina as a section having no especially distinct characters. 



Section Chlamydoglyphis Pilsbry. 



Shell thin, oblong, low-conical or depressed ; orifice rather large, 

 oval, situated in front of the middle ; surface distinctly cancellated ; 

 internal hole-callus truncated behind ; basal edges of the shell in 

 one plane, not elevated at the ends ; margin finely crenulated. 



Animal in general characters much like that of Megatebennus, 

 higher behind, depressed in front, the mantle covering about a 



