TRANSACTIONS OF WAGNER 

 1436 



TERTIARY FAUNA OF FLORIDA 



southeastern Alaska, at a depth of three hundred and twenty-two fathoms, 

 muddy bottom ; bottom temperature 42.4 Fahr. 



This peculiar shell was reported to exist in some Pliocene beds cut through 

 in grading streets in Los Angeles in considerable numbers, but poorly pre- 

 served. Specimens were submitted to me by Dr. Cooper for examination and 

 comparison with the types in 1893. 



FAMILY CONDYLOCARDIID^. 



This family was instituted by Bernard for some extremely minute bivalves, 

 related to the Carditida, but which retain in the adult state the immaturity of 

 hinge characters which characterizes the nepionic shells of Cardita, and, more- 

 over, have the resilium sunken and centrally located between the valves. The 

 prodissoconch in this group is of the usual size, but appears very prominent 

 on account of the relatively small additions made to it in growth. As in Car- 

 dita, the margins have sometimes a projecting border externally, which, under 

 magnification, appears quite prominent, but in the larger forms now added to 

 the family is not especially noticeable. 



The following groups comprise this family : 



Genus Erycinella Conrad, 1845. Type E. ovalis Conrad. Fossil in the Mio- 

 cene of Virginia and the Crag of Britain. 



Shell small, oval, radially sculptured, with an external ligament and internal 

 resilium situated between the cardinals, of which there are two in each valve ; 

 in the left valve the edges of the resiliary chondrophore are somewhat raised, 

 so that when worn the valve appears to contain four cardinals, but I think these 

 ridges are not of the nature of true teeth ; in the right valve the posterior 

 cardinal is stout, and triangular and feebly grooved ; there is a feeble, elongate, 

 posterior right and anterior left lateral which fits into a groove in the margin 

 of the opposite valve ; the inner margins of the valves are crenulated. 



The E. ovalis of Wood, from the Crag beds of England, is not the same 

 species as the one described by Conrad from the Yorktown Miocene of Vir- 

 ginia, as I have determined from an examination of typical specimens. In 

 his description Wood has regarded the raised edges of the chondrophore as 

 teeth. In this species the ligament is much reduced and is set in a small chink 

 directly between the umbones, so that it is concealed (though not internal) 

 when the two valves are united, thus being in marked contrast to that of E. 

 ovalis Conrad, which is set on a well-defined lateral nymph. 



