1902.] NATURAL SCIENCES OF PHILADELPHIA. 701 



Subfamily THBOALIIN^. 

 Genus THECALIA H. and A. Adams, 1857. 



Type T. concamerata Bruguiere (sp, ), South Africa. 



Shell like a small Carditamera externally; the female has in each 

 valve a funicular infold of the inner layer of the shell to serve as 

 a marsupium, which, when the valves are closed, is completely 

 internal ; the male only a small byssal gape in the same region. 

 Hinge with two cardinals in each valve, the posterior right cardinal 

 absent, the middle right cardinal large and produced behind ; there 

 is an anterior lateral in each valve. The eggs are discharged into 

 the marsupium, which is lined by a fold of the mantle, and remain 

 there until the young shells are well advanced beyond the prodis- 

 soconch stage. 



Genus MILNERIA Call, 18S1. 



Type Ceropsis minima Dall, 1871. Recent. California. 



Shell very small and trapezoidal, flattened on the ventral side ; 

 the female with a dome-like indentation of the ventral margins of 

 the valves, which is closed below only by a fold of the mantle and 

 not included within the closed valves ; hinge with two left and three 

 right cardinals, the posterior left lateral, posterior and anterior 

 right cardinals minute and recognizable only in the best-developed 

 specimens, which have the formula ^ o loioi • '^^^ "^^^® ^^ byssi- 

 ferous and the species habitually nestles on flat surfaces, particu- 

 larly the backs of Haliotis shells. 



The name Ceropsis being preoccupied since 1839 in Coleoptera 

 by Solier, it was replaced by Milneria. The young are incubated 

 as in Thecalia. 



Cabralia (Schmitzii) Boehm, 1899, from the Miocene of the 

 Azores, was referred to the Carditidce, but appears to belong in the 

 VeneridcB near Venerupis, its hardly sinuated pallial line being 

 paralleled in Chione, etc. 



Family OONDYLOCARDIID^. 

 Genus ERYCINELLA Conrad, 1845. 



Type E. ovalis Convsid (not of S. Wood). Miocene of Virginia. 



Shell small, oval, radially sculptured, with the ligament external ; 



the resilium internal and placed medially between two cardinals in 



