SCIUROMORPHA. 837 



a little wider anteriorly^than others. On a specimen presenting the narrowed 

 form the name cristatus was proposed. In some specimens the inferior 

 incisors are more compressed than in others. In some of the specimens the 

 original bright-bay color of the enamel of the superior and inferior incisors 

 is beautifully preserved. 



Measurements. 



M. 



Length of inferior mol.ars 0.0140 



Length of penultimate molar .0033 



Width of penultimate molar 0035 



W'iiith of first molar 0030 



Length of first molar 0035 



Depth of jaw at penultimate molar 0090 



Depth of incisor-tooth .0040 



Width of incisor-tooth 0020 



The olecranar fossa of the humerus has a small perforation. There are 

 two small rather deep fossae on the posterior aspect of the humerus distally ; 

 the larger is at the base of tlie epicondyle, the other is within and a little 

 above it. The marginal crest from the external epicondylar region is arcute 

 and rather elongate. The shaft of the humerus above it is quite slender. 

 In a second specimen, the inner of these two fossae is wanting. At the 

 middle of the shaft of the tibia, the anterior and external faces meet at a 

 right angle ; the inner and posterior, faces. Jorm a nearly continuous curve. 

 The inner crest of the posterior distal process, which bounds the sulcus 

 tendinis flexoris longi poUicis is not so produced as in Gymnoptyclms minutus, 

 or Ardomys monax. The humerus bears considerable resemblance to that 

 of both these species, but differs from both in the presence of the posterior 

 fossae. In Ardomys monax the arterial foramen is wanting. 



Measurements. 



u. 



Diameter distal end of humerus ^^°'«^''P"^*'^"''^ *^50 



( transverse 0190 



Length of internal epicondyle 0060 



Diameter distal extremity tibia ^ anteroposterior 0060 



( transverse 0080 



r.. . r, r i- < exterointernal 0060 



Diameter of base of uium ^ 



( anteroposterior 0065 



Anteroposterior diameter of aeetabnlnm 0065 



Length of astragalus (axial to foot) 0100 



Length of astragalus obliquely 0115 



Width of trochlea of astragalus 0060 



Width of head of astragalus 0045 



Elevation of external arc of astragalus 0045 



