124 KANSAS UNIVERSITY QUARTERLY. 



Cardiocei-ds cordifovme Meek. Plate XXVII, figs. 1-12. 



Shell from medium to large size ; cross-section of outer volution 

 near the aperture nearly triangular ; the dorsal side of the outer 

 volution sloping gradually to a rather prominent keel in the shell, but 

 to a rounded margin in the cast. The ventral side of the volution 

 passes almost vertically to the inner volution, and in old individuals 

 forms a reentrant angle with the inner volution. The outer volution 

 of the shell expands rapidly toward the aperture, at which point it 

 equals about one-third the full diameter of the shell. The umbilicies 

 equal in diameter nearly one-third of the outer volution. The surface 

 of the shell is marked by transverse, tlexuous costte, which are some- 

 what variable in prominence and are frequently bifurcated at one- 

 fourth the distance from the dorsal to the umbilical border. The 

 bifurcated costfe are separated by a simj^le costa, which fades out be- 

 fore reaching the umbilical border. The costse form a sigmoidal curve 

 in passing from the dorsal to the umbilical border. 



The septa are marked on but few of the sandstone casts; they are 

 somewhat crowded. The dorsal lobe is higher than wide, and has 

 two terminal lobes, each ornamented with numerous smaller digita- 

 tions. It also possesses two lateral lobes similarly ornamented and 

 followed below by two minor lobes. The dorsal saddle is somewhat 

 narrower than the dorsal lobe, and is pierced at the terminus by a 

 small lobe, and laterly by the lateral branches of the adjacent lobes, 

 which form for it one terminal and five lateral branches. The first 

 lateral lobe nearly equals in length the dorsal lobe ; it is ornamented 

 by three terminal and two lateral branches, each having minor digi- 

 tations. The first lateral saddle is much narrower than the first 

 lateral lobe, and is ornamented with two small terminal branches and 

 several lateral ones, all of which are unequally digitate. The second 

 lateral lobe is a little more than half the size of the first, and lias two 

 terminal digitate branches and two smaller lateral ones. The re- 

 mainder of the septum is not present in a determinable condition in 

 any of the specimens collected. 



Dimensions : Diameter of a medium specimen, 80 mm ; diameter 

 of an outer volution, 35 mm. 



Geological horizon : Species occurs in moderate abundance in the 

 clay and arenaceous nodules of No. 13 of the section. It is associated 

 with Astarte packardi, Belem7iites densus, Piirna kingi, etc. 



Locality : Freeze-out Hills, Wyoming, and Black Hills, Dakota. 



Remarks : This species seems to be closely related to the northern 

 European species Cardioceras {Quenstedioceras) lamherti, which 

 is described from Russia. 



