292 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



defined upon botli the inner and outer surface ; the margin of the aper- 

 tures not being even everted or raised ujion the outer surface. More- 

 over, these perforations exist upon the middle portion of the valve only, 

 the greater part of the rows extending from the umbo to the basal border. 

 In the young state, as shown on the umbo of adult shells, a lesser part 

 of the median interspaces were thus perforated, but as the shell grew 

 perforations were introduced into the next outer adjoining interspaces, 

 so that fully one-half of the surface of the adult shell was occupied by 

 them. Both the anterior and posterior i)ortions of the surface, compris- 

 ing a considerable proportion of the ribs which mark the surface, are 

 entirely without either holes or spines, and besides the ribs, the surface 

 is marked only by the ordinary lines and imbrications of growth. 



This shell therefore differs from the typical forms of Criocardium in 

 having perforations only instead of spines or nodes upon the intercostal 

 interspaces ; and in having neither spines nor perforations upon either 

 the anterior or posterior portions of the valves, upon which portions in 

 Criocardium the spines are more conspicuous than upon the median por- 

 tion. These differences from Criocardium are certainly as great as those 

 which separate any of the other recognized subgenera of Cardium, and 

 this shell is therefore as worthy as they of subgeneric designation. I 

 therefore propose for a section of the genus Cardium, of which C. specio- 

 sum Meek & Hayden is the type, the subgeneric name of Etlimocardium. 



Washington, December 2, 1879. 



DESCRIPTIONS OF NEW CRETACEOUS INVERTEBRATE FOSSIIiS 

 FROm KANSAS AND TEXAS. 



By C. A. Tl^HITE. 



Of the fossils described in this paper the two Avicuhds were discov- 

 ered by Prof. B. F. Mudge,* in strata of the Dakota Group, in Saline 

 County, Kansas, and sent by him to the National Museum. The locality 

 of these fossils is only about three miles distant from that at which he 

 obtained a series of fossils which were described and figured in vol. ix, 

 U. S. Geol. Surv. Terr. (4to ser.). They are all from the Dakota Group, 

 and all evidently from the same local horizon, because at least two of 

 the associated species are identical with two which were among those 

 described by Mr. Meek, and just referred to. 



AH the remainder are froin Texas, having been sent respectively by 

 Mr. G. W. Marnoch, from Bexar County ; Mr. D. H. Walker from Bell 

 County, and Mr. S. W. Black, from Collin County. The types of all 

 these species are now in the collections of the National Museum. 



* While these pages are passing through the press the sad intelligence comes that 

 Professor Mudge is dead. He was a sincere devotee and an intelligent interpreter of 

 nature, and, better still, an honest man. Peace to his ashes. — C. A. W. 



