TRANSACTIONS OF WAGNER 



1 3 TERTIARY FAUNA OF FLORIDA 



latinized) ; V. subrugosa Lamarck ; not Triquetra Conrad, 1846, or Herrmannsen, 



after Klein, 1849. 



Triquetra Anton, Verzeichn., p. 10, 1839; V. fluctuosa L. 

 Cryptogramma Morch, Cat. Yoldi, ii., p. 22, 1853. First species V. subrugosa Wood ; H. 



and A. Adams, Gen. Rec. Moll., ii., p. 420, 1857 ; Romer, Mai. Blatt., xiii., p. 20, 1867 ; 



V, ftexuosa L. ; Stoliczka, Cret. Pel. India, p. 148, 1871 ; Tryon, Syst. Conch., iii., p. 



176, 1884; Fischer, Man. de Conchyl., p. 1083, 1887. 

 Anomalocardia Deshayes, Cat. Conch. Brit. Mus., i., p. 115, 1853; Romer, Krit. Unters., 



p. 17, 1857; Dall, Bull. 37, U. S. Nat. Mus., p. 54, 1889. 



This group is distinguished by its general aspect and similarity of the species 

 rather than by strongly marked characters, and if it had not been generally 

 accepted I should have been tempted to regard it as merely a subgenus of 

 Chione. 



The dental formula is L - IOIOI -. The teeth are entire and rather slender and 



R. oioioi. 



diverge widely from their common centre. The upper side of the posterior left 

 cardinal and the lower edge of the right nymph are usually minutely rugose. 

 The external sculpture usually is of coarse, more or less confluent, concentric 

 ribs, with obsolete radial striae, though when the shell disintegrates under the 

 influence of decay it is seen to have internally a strong radial element in its 

 structure. This hidden radiation probably suggested to Morch the name he 

 applied to the genus. The sculpture of the shell is often obsolete at the middle 

 of the valves, which in the typical group are covered by a vernicose olivaceous 

 periostracum. The inner margins are crenulate and the valves attenuated and 

 more or less nasute behind. The ligament is exposed and rather short; the 

 lunule and escutcheon impressed, the posterior right dorsal margin grooved to 

 receive the edge of the opposite valve. The beaks are rather pointed in most 

 of the species and the pallial sinus is very small, angular, and sometimes almost 

 obsolete. Most of the species are very solid and heavy. A species (A. leptalea 

 Dall) from the lagoons of Watling's Island, Bahamas, differs from all the 

 others in its extreme thinness and less prominent beaks. As this is probably 

 the direct result of the very warm and excessively salt water it inhabits, it 

 seems hardly necessary to give it sectional rank. The colors of the shell, apart 

 from those of the periostracum, are usually white and purple ; a Florida species 

 is marked also with a zigzag pattern of brown, sometimes broken up into clots. 

 The Pacific coast A. subimbricata forms a- transition towards Chione. The 

 left posterior and right anterior cardinals in the type are feeble ; the latter in 

 the oriental species is frequently obsolete, so that the valve appears to have 

 but two cardinal teeth. The genus may be divided into the following sections : 



