13 



American East Coast Arcas 13 



Gualt. test. 91./. F. 



Ars^oiv. conch, t. 2$./- M. 



Habitat in M. Mediterraneo. 



" Testa apice rotundata, integra; strict ex ptmctis callosis concatenatis: alternis stfiis majori- 



bus. Barba ex striis versus apicem imprimis tenuiorem rigens." — Linne, 1758. 



This species is irregularly colored with light and dark brown, the ribs are granulated, 

 numerous and fine with slightly larger ribs at intervals on the middle of the valve; epi- 

 dermis bristly; teeth fine at the center of the hinge, long and oblique distally; ligament 

 area with several v-shaped grooves; inner margin smooth; byssal opening usually small. 



Dimensions. — Lon. +17,-32; alt. + 5, -22; diam. 20mm. 



Occurrence. — Recent from North Carolina to Barbados. — Dall. Recent from the 

 Mediterranean, Florida and the West Indies. — C. U. Museum. This is a common re- 

 cent and fossil European species. 



Area cuculloides Conrad 



Plate II, Figures 8, g, 10, 11, 12 



Area cuculloides. Conrad, Fos. Tert. Form., p. 37, 1833. 



Byssoarca citculloides Conrad, Am. Journ. Sci., 2d. ser., vol. i, p. 219, 1846. 



Byssoarca lima Conrad, Acad. Nat. Sci. Phila., Proc. for 1847, p. 295; Journ., 2d. ser., vol. i, p. 



125, pi. 13, fig. 23, i848=/4. Conradi Deshayes. 

 Not Area lima Reeve, Conch. Icon., Area no. loi, 1844. 



Navicula cuculloides el lima Conrad, .\cad. Nat. Sci. Phila., Proc. for 1854, p, 29. 

 Cucullccarca lima el cuculloides Conrad, Am. Journ. Conch., vol. i, p. 11, 1S65. 

 Barbatia (Calloarca) cuculloides Dall, Wagner Free Inst. Sci., Trans. , vol. 3, pt. 4, pp. 615, 624, 



1898. 



"Shell compressed, thick, inequivalve, reticulated; with a broad subcentral sinus, 

 passing from the beak to the basal margin: posterior side elongated, strongly ribbed, and 

 carinated; anterior side with numerous striae; anterior end truncated. Length 2 J^ in- 

 ches. Breadth 1% inches. 



"The hinge of this shell approaches cucullaea, in the interval between the beaks, hav- 

 ing arcuated grooves under the beak; line of series of hinge teeth widely interrupted, 

 and transverse at the extremities. 



"Locality. Claiborne, Alab. 



"Cab. Acad. N. S." — Conrad, 1833. 



Ribs smallest near the middle of the valve, becoming wider and smoother toward 

 the umbonal ridge and larger and more widely spaced anteriorly; posterior slope with 

 small, smooth ribs, this region separated from the rest of the shell by a sharp radial 

 ridge which is often serrate; ribs anterior to the umbonal ridge mostly nodular and with 

 finer ribs in some of the interspaces; cardinal area longer behind with numerous regular 

 grooves; teeth continuous in the young, those in the center very small, distal teeth long 

 and oblique, usually irregular in old specimens; outHne variable, shell higher posteriorly. 

 The ribbing varies on different shells, but the species is characterized by the sharp rib 

 down the umbonal ridge and the ribs usually are quite different on different parts of the 

 shell. 



