GLIRES OF THE SANTA CRUZ BEDS. 473 



the individuals which Ameghino described and figured in his great work 

 ('87*, p. 214, PI. X, figs. 8-1 1). The species is one of the larger and more 

 robust members of the genus ; the incisors are relatively large and stout 

 and m- has a long, incurved posterior process. The lower premolar is 

 very variable in form ; the anterior prism may be smaller, or larger than 



FIG. 46. 



c 



Eocardia montana, lower grinding teeth, x f . a. Right side, crown view. b. Right side, 

 external and crown views, A. M. N. H. c. Left side, crown view, A. M. N. H. 



the posterior, of elliptical, elliptico-triangular, or triangular cross-section, 

 and with or without a groove on the anterior face ; when present, the 

 groove is shallow. In one individual (Fig. 46, b, A. M. N. H., No. 9,526) 

 there is a low, but quite distinct pillar on the anterior prism, set off by a 

 fine hairlike groove on each side of it. The mandible is stout. 



One specimen (No. 15,385) which I refer to this species, though of 

 unusually small size, consists of a much flattened skull, lacking the cranial 

 roof and mandible, and several fragments of vertebrae and limb-bones. 

 The absence of the mandible makes the reference somewhat uncertain. 

 The specimen is remarkable for the small size of p-, for the heavy rostrum, 

 which tapers anteriorly, and for the thickness of the zygomatic arch, espe- 

 cially of the zygomatic process of the maxillary. 



MEASUREMENTS. No. No. No. 



15,574- 9,526. 15372. 



Lower dentition, length 039 .039 



" " " p T -nij 019 .018 .019 



Lower incisor, width 003 .003 



" " thickness 004 .0x335 



P f , length (i. e., antero-posterior diameter) 0x34 .0x34 .004 



" width (/'. e., transverse diameter of anterior prism) 0025 .0025 .0x325 



Mandible, depth at pj OIO .010 .010 



" length from condyle .050 



The following measurements are from the specimen of doubtful refer- 

 ence, mentioned above (No. 15,385) : 



