118 TRANSACTIONS OF THE WAGNER FREE 



cordiform lunule ; hinge-tooth (in right valve) an elongated lamellar plate, 

 which advances beneath the lunular depression (where it is thickened), and 

 is received into a corresponding sulcus in the left valve ; external surface 

 radiately ribbed, the ribs about sixteen in number, profoundly elevated, 

 narrow much narrower than the interspaces and strongly knobbed or 

 serrated, those of the posterior slope irregular in size; base creno- 

 carinated. 



Length, 1.3 inch ; height to the top of umbo, one inch. 



This species bears a close resemblance to the recent C. laticostata, but 

 may be distinguished by the narrowness of its ribs as broad as or broader 

 than the interspaces in the recent form and the prominence of its um- 

 bones. 



Area imbricata, Bruguiere. 



Encycl. Mth., 1789, p. 98. 



Gabb, "Santo Domingo," Trans. Am. Philos. Soc., xv, p. 254. 



A number of individuals, which are practically identical with the 

 recent forms from Key West, Fla. (from the collections of Hemphill), and 

 the Miocene fossil of Santo Domingo (Area Noizt of Guppy, Q. Journ. 

 Geol. Soc. London, xxii, p. 293). The species is also very closely related 

 to, if not identical with, the Mediterranean A. tetragona of Poli. Area 

 ocellata, Reeve, from the coasts of the Malay Peninsula, so nearly resembles 

 the Florida fossil as to be barely distinguishable from it. The only points 

 of difference appear to be a more pronounced angulation (in the eastern 

 shell) of the posterior slope, and the lack of radiating lines on the basal 

 portion of this slope. Area protracta, Conrad, from the Oligocene de- 

 posits of Vicksburg, is a close ally, but is a much more elongated shell, 

 and has the posterior border emarginated or sinuous, instead of direct. 



Area Listeri 1 Philippi. 



Abbild. und Beschreib. Conchyl., iii (1851), p. 87. 



I have identified with this form a number of arks undistinguishable 

 from a recent species of the South Florida coast, which Mr. Tryon has 

 determined to be Lister's species. I am not absolutely satisfied as to the 

 correctness of this determination, since the recent Florida shell lacks the 

 peculiar light color stripe which, according to Philippi's description, 

 would appear to be characteristic of his species, and has the umbonal 

 region in addition less inflated. The general habits and other characters 

 are, however, the same in both forms. Gabb's Barbatia Bonaczyi, from 

 the Miocene of Santo Domingo, appears to be identical with the 

 Florida form. 



Area aronla, nov. sp. Fig. 65. 



Shell moderately elongated, sharply angulated on the posterior slope, 

 the dorsal and ventral borders nearly straight and parallel with one 



