TRANSACTIONS OF WAGNER 

 I 326 



TERTIARY FAUNA OF FLORIDA 



other and the animal is byssiferous. The distribution is in the Old World 



temperate and tropical regions. 



xj-YV" 1 / 



X' This is Amygdala Romer, 1857, not of van Phelsum, 1/74; Cuneus H. and 

 A. Adams, but not of Da Costa; it is not Amygdalum Megerle. 



Section Ruditapes s. s. (vide supra}. 



Subgenus Protothaca Dall, 1902. Type Venus Dombeyi Lamarck,= V . thaca 

 (Molina) Orbigny, = Chama thaca Molina.^) 



Shell ovate, moderately convex ; coloration usually whitish or dull ; sur- 

 face not polished, reticulately sculptured, the radials usually stronger ; sculp- 

 ture more or less distinctly divided into three areas, the middle of the valves 

 being chiefly radial, the anterior radial and scabrous, the posterior irregularly 

 concentric ; the lunule is sharply circumscribed and the escutcheon of the left 

 valve ; the right valve in the type has no corresponding portion of the escut- 

 cheon and the margin somewhat overlaps that of the left valve, but does not 

 conceal the ligament ; the middle cardinals are usually grooved or bifid ; the 

 pallial sinus of moderate size, nearly horizontal, free below and pointed in 

 front ; the inner margins are sharply crenulated ; the siphons are short, united, 

 and only the incurrent orifice is papillose ; the foot is hatchet-shaped and not 

 byssiferous. 



The distribution of this group includes the west coast of South America, 

 Japan, and New Zealand (V . costata Quoy). 



Section Callithaca Dall, 1902. Type Tapes tenerrima Carpenter. Cali- 



*-. fornia. 



Sculpture uniform over the disk (except in nestling individuals) ; the 

 lunule feebly defined, the escutcheon not defined ; the dorsal margin not over- 

 lapping in the right valve, the inner margins entire ; otherwise as in the pre- 

 ceding group. 



The species of this subgenus are distributed along the shores of the North 

 Pacific in America and Japan. The type dates back to the Miocene in time. 

 It was referred to Saxidomus as a sulcate section by Deshayes in 1853. Most 

 of the species are yellowish white with a dull surface, but some of the snore 

 southern ones are prettily maculated with brown. There is no byssal groove 

 in the hatchet-shaped foot, and the papillose siphons are united to their tips in 

 the type species. Callithaca is Californian. 



It may be observed here that most of the European forms of Paphia have 

 the siphons more or less united, the minority having them completely free from 

 each other, while the American forms which have been examined have the 



