TRANSACTIONS OF WAGNER 

 882 



TERTIARY FAUNA OF FLORIDA 



ligament marginal, set off by a prominent lamina of shell from the pit ; left car- 

 dinal with a very short posterior arm projecting over the pit, with an accessory 

 lamella above apprcssed to the ligamentary ridge over the apex of the chon- 

 drophore ; a single obsolete and very short lateral in each valve before and 

 behind the pit ; hinge-plate flattish behind, depressed and excavated in front. 



A single species on each shore of America inhabiting the warmer re- 

 gions. Geologically the group goes back to the Pliocene. 



Subgenus RAETA Gray, 1853. 

 Type Lutraria caiia/ii ulata Say, 1822. 



Shell large, inequilateral, thin, inflated, acutely rostrate behind, concen- 

 trically plicate; dorsal areas obscure, the surface of the valves more or less 

 vermiculate ; pallial sinus deep, narrow, pointed ; siphonal gape small ; liga- 

 ment submerged except at the anterior end, set of by a shelly ridge which 

 roofs the apex of the pit and partially supports the posterior arm of the 

 cardinal tooth; dental armature concentrated ; chondrophore large; left car- 

 dinal small, its posterior arm shorter, with a small accessory lamella above, 

 both projecting over the pit; right cardinal with the arms coalescent above, 

 the anterior larger, superposed on a feeble anterior lateral, the posterior arm 

 much shorter, projecting over the pit ; a single anterior and posterior lateral 

 in each valve but no paired laminae. 



Distribution the same as Labiosa. Geologically the group goes back to 

 the Miocene. 



Section Raetina Dall, 1894. 

 Type R. indica Dall n. s. 



Shell like Ra'eta but small, with the posterior laterals wholly wanting ; 

 the hinge-plate normal, its ventral margin not upturned ; the anterior sinus 

 excavated, and roofed at the apex.* 



Subgenus RAETELLA Dall, 1894. 



Type R. tennis Dall.f 



Shell very small and thin, surface concentrically plicate, not vermiculate, 

 polished ; dorsal areas well defined ; sinus short and rounded ; valves inflated, 



* R. indica n. s. Shell white, elongate, concentrically finely plicate, very thin ; pallial sinus 

 very deep and narrow ; beaks small, inflated, nearer the anterior end, which is full and rounded, the 

 posterior end being produced, attenuated, and laterally compressed, forming a bluntly pointed rostrum. 

 Alt. of shell 28.5, Ion. 43, diam. 20 mm. 



Bombay, U. S. Nat. Mus.,No. 90,276. 



This species resembles A', rostralis Deshayes ( = pulchelhi Ad. and Rve.) but is larger, while in 



