wawhw.] CARDIID.& W 



CARDIID/E. 



Genus CARDIUM Linnaeus. 



Cardium PAUPBBOULiJii Meek* 



PL xxii, Pigs. 9-12. 



Cardium paupereulum Meek, 1871, Ann. Kept. I'. 8. Geol. 8ur. Terr, for 1870, p. 300; 

 White, 1870, idem for L877, p.291, PL 9, Fig. 3a. 



Cardium subeurtum Meek, 1873. idem for 1872, p. 470; 1877, IT, 8. GeoL ExpL 10th Par- 

 allel, vol. iv, p. 152, PI. 15, Pig. 3*. 



Original description : 



"Shell small, very thin, rather compressed, subovate or subcircular; 

 beaks moderately prominent and nearly central; .surface ornamented 

 by about thirty regular, simple, distinctly defined, radiating costae, 

 which about equal the intermediate furrows, and (owing to the thinness 

 of the valves) are well defined internally, and thus impart a plicated 

 or crenated character to the margins; crossing these are numerous 

 very regular, well-defined, delicate marks of growth that are usually 

 l<-ss distinct on the posterior third, but givea neatly crenulated appear- 

 ance to the costa; farther forward. 



u The specimens yet seen of this little shell are rarely more than 

 about 0.50 inch in diameter, and are all more or less flattened or other- 

 wise distorted. Sometimes they are distorted by anteroposterior 

 pressure, so as to present somewhat the appearance' and outline of a 

 Lima, being higher than wide, and more or less oblique, while in other 

 examples they are distorted by vertical pressure, so as to present little 

 or no obliquity, and to show a greater anteroposterior diameter than 

 height. I have not seen the hinge, but some impressions in the matrix 

 show that it has anterior and posterior lateral teeth like those of Car- 

 dium; it, however, does not belong properly to the typical section of 

 that genus." 



The types are distorted internal casts and molds of the surface, some 

 of which show the natural form, and Meek's figure published by White 

 (loc. cit.) is an incorrect restoration. The comparison of a large series 

 of specimens in all states of preservation has fully established the iden- 

 tity of Cardium subewtum with C. paupereulum. The sandstone casts 

 to which the former name was given were thus described: 



"Shell under medium size, truncato-suborbicular, about as high as 

 wide, rather convex, and but'very slightly oblique; beaks nearly cen- 

 tral, rather prominent, distinctly incurved almost at right angles to the 

 hinge; posterior margin truncated with a slight forward obliquity, so 

 as to connect with the dorsal margin at an obtuse angle; anterior mar- 

 gin rounding regularly into the base, which describes a slightly oblique 

 semiovate curve, being more prominent behind, where it rounds up 

 very abruptly to the ])osterior margin, so as to give a subangular out- 

 line to the posterior basal extremity ; umbonal slopes rather prominent, 



