TRANSACTIONS OF WAGNER 

 I22A 



TERTIARY FAUNA OF FLORIDA 



sertation for the doctorate of philosophy a " Kritische Untersuchung" of the 

 Linnean genus Venus, in which a systematic arrangement of the species was 

 proposed which has had a strong influence on subsequent literature of the 

 subject. Unfortunately, Romer's ideas of nomenclature were rather bizarre; 

 he divided his subgenera into " families," and proposed new names to cover 

 groups composed of genera of older date which he reduced in rank. Though 

 his paper contained a vast amount of information, his disregard of the rules 

 and ignorance of certain works bearing on the nomenclature of the group 

 render his arrangement more or less defective. Later this author prepared a 

 number of monographs of groups of Veneridaz, with very beautiful and accu- 

 rate plates, which will permanently associate his name with the study of this 

 attractive group of Mollusks. 



The reviews of the genera in Stoliczka's " Cretaceous Pelecypoda of India," 

 1871, and Fischer's painstaking " Manuel de Conchyliologie," 1887, must be 

 consulted by all students of the Veneridce. A revision by the writer, covering 

 the family Veneridce, was published in the " Proceedings of the U. S. Nat. 

 Museum," xxvi., No. 1312, pp. 345-366, 1902. 



This family is here divided into four subfamilies, Dosiniina, Meretricina, 

 Venerince, and Gemmine. 



Subfamily DOSINIIN/E. 



This group is composed chiefly of orbicular shells with concentric sculpture, 

 which have a large arcuate foot and long, closely united siphons. The hinge, 

 except in dementia, which is somewhat degenerate and has the hinge much 

 reduced in relative size, has three left and four right cardinals. There are 

 usually no posterior laterals, and the anterior laterals, when present, are usually 

 practically obsolete. 



The group recedes in time to the Eocene and has never been very abundant 

 in species. A number of species have been described from the Cretaceous and 

 even from the Jurassic, but, as Stoliczka has pointed out, these are mostly not 

 true Dosinias, but belong to Cyprimeria and other groups which are precursors 

 of the Venerida. 



The earlier representatives of the subfamily have a corrugated area on the 

 adjacent surfaces of the nymphs and posterior lateral teeth, and it is interest- 

 ing to note that in the nepionic young of Dosinidia, sometimes even up to a 

 size of ten millimetres, this corrugation is retained, though, as the shell grows, 

 it becomes obscure and finally disappears. As in many shells with broad 



