TRANSACTIONS OF WAGNER 

 1482 



TERTIARY FAUNA OF FLORIDA 



Other morphologic features than to Astarte, which agrees in that particular 

 especially. Lirodiscus by its flattened umbones recalls Scambula, and in the 

 characteristics of the periostracum the two families are also similar. Crassa- 

 tellites for some reason has succeeded in occupying a place in the warmer seas, 

 while the Astarte type in the main is a denizen of the colder waters, the species 

 entering the milder zone being invariably of small size. Correlated with the 

 difference of habitat is the greater tendency to develop color or color markings 

 in Crassatellites. 



My observations on the hinge agree essentially with Bernard's as regards 

 variability and the development or abortion of particular elements of the den- 

 tition. I have not found, however, traces of more than three cardinals in eifher 

 valve, the number actually figured by Bernard. The hinge-formula is as 

 follows: ^ °'°'°'°' . 



R. i.oioiol.o 



The laterals are formed by an extension of the valve-margin, which fits into 

 a socket on the edge of the opposite valve ; they usually alternate, one socket 

 and one lateral to each valve. Bernard has formulated the edges of the socket 

 as two laterals, but this seems hardly worth while. The middle cardinals are 

 usually strongly developed and sometimes longitudinally striated or bifid ; the 

 anterior right and posterior left cardinals are nearly always (and the posterior 

 right cardinal frequently) obsolete, or represented by mere traces; the other 

 teeth in the adult are usually well marked. Like Crassatellites and Cardita, 

 the sides of the cardinals may, and frequently do, develop more or less trans- 

 verse striation ; in Astarte proper this feature is more common in the fossil 

 than in the recent species. 



No Astarte has radial ribbing, but many of them develop crenulations on 

 the inner margins of the valves when adult, or at the resting stages of the 

 practically mature individual. Between these stages the same individual may 

 be destitute of crenulations, while, on the other hand, some species always, and 

 others never, have them. A peculiarity which has been noticed in several of 

 the genera of Astartidce is the tendency to reversal of the hinge-teeth in rela- 

 tion to the valves, the dentition normal to the right valve being found in the 

 left, and vice versa. This peculiarity is especially notable in Goodallia, where, 

 out of one lot examined, nearly one-third had the hinge reversed. The strength 

 of the laterals is also very variable ; some species have them strong and promi- 

 nent, in others they are almost wholly obsolete, with every intermediate grada- 

 tion in the series of species. 



The distinctions upon which the groups under Astartidce are based are 

 chiefly those of greater or less development of the hinge-teeth and differences 



