TRANSACTIONS OF WAGNER 



1404 



TERTIARY FAUNA OF FLORIDA 



It is best discriminated from the allied C. ferruginea Reeve, of the same faunal 

 region, by the fact that the other species is attached by the right valve, and 

 when colored is usually of a reddish brown, with sharp radial striation on the 

 foliations, which are more or less restricted to radial rows. 



C. ferruginea; C. variegata Reeve, 1847; C. iiorida Lamarck, 1819 {-{- C. 

 sarda Reeve, 1846), and C. lactuca Dall, 1886, species now existing on the 

 coast, are not yet reported in the fossil state. 



Since the above account of our Chamas was prepared Aldrich has described 

 and figured in the " Nautilus" (xvi., p. 100, pi. iv., fig. 15, Jan., 1903) Chama 

 monroensis from the Eocene Ostrea sellceformis bed at White's marl-pit, Monroe 

 County, Alabama. It is a lamellose species with paired radial riblets. 



Genus EOHINOCHAMA Fischer. 

 Arcinella Schumacher, Essai, p. 142, pi. xiii., fig. i, 1817 (type Chama arcinella Linne) ; 



Morch, Cat. Yoldi, ii., p. 37, 1853 ; Sowerby, Man. Conch., 2d ed., p. 72, 1842 (not 



Arcinella Oken, Lehrb. der Naturg., viii., pp. 236, 238, = Cardita Brug. ; or Arcinella 



Philippi, Enum. Moll. Sicil., ii., p. 53, 1843, Mytilidce). 

 Echinochama Fischer, Man. de Conchyl., p. 1049, 1887. Type Chama arcinella Linne. 



The presence of a large and impressed lunule, the peculiar surface, the 

 nearly free habit in the adult state, and the large protoconch separate this group 

 suf^ciently from the genus Chama. The number of species is small. The type, 

 which is West Indian and Pliocene, and E. calif ornica Dall, from Lower Cali- 

 fornia (which differs from E. arcinella by its flatter, larger, and more quadrate 

 valves, less prominent beaks, less impressed lunule, more numerous ribs and 

 longer spines), are not yet known in the fossil state. The following species 

 carries the group back to the Oligocene. All the species adhere when young 

 by the right valve. 



Echinochama antiquata n. sp. 

 Plate 54, Figure 9. 

 Chama arcinella Guppy, Geol. Mag., dec. ii., vol. i., p. 450, 1874; not of Linne. 



Oligocene of Bowden, Jamaica, and Haiti, West Indies. 



Shell large, subquadrate, with an almost absolutely rectilinear base, slightly 

 arched posterior and dorsal edges, and excavated anterior end ; valves less con- 

 vex than in E. arcinella and with less prominent and inflated beaks, larger and 

 less impressed lunule; the number of ribs varies from twenty-two to thirty- 

 one, low with subequal interspaces, the spines very short and scalelike except 

 on a single median rib, where they are triangular and somewhat longer than on 



