THE MAMMALIA OF THE UTNTA FORMATION. 521 



The anterior crest is lofty, bilobute, with a distinct anterior valley and buttress; the 

 posterior crest is low, especially at the postero-internal anj^le. As shown in Fig. 11, 

 the second and third premolars were bifanged, while the first premolar had a single 

 fang and abutted closely against the canine as in I. laUdens. 



The Skeleton. 



Axial. The vertebral and other portions of the skeleton, associated with the 

 second specimen (No. 10,-101), indicate that Ihey belong to a young indiv idual. All 

 the verteliral centra, lacking the epiphyses, and the contours of the posterior faces of 

 the carpals being incompletely developed. The vertebrm belong to the posterior dor- 

 sal and lumbar region ; the centra are much flattened vertically and slightly keeled. 

 Fragments of the cranium and infi\ioi'l)ital region are present, but arc not character- 

 istic. 



Ap2)e)icUcular. Fore limb. The .sea[)ula has a suboval glenoid lace, with a 

 raised anterior border and the base of an ai)parently prominent coracoid process. 

 The distance between the outer border and the rise of the spine is very narrow, in- 

 dicating a rather short neck. The proximal portion of the radius presents a limited 

 lateral extension, with rather deep antero-posterior diameter. These proportions, 

 taken in connection with the rather broad carpus, indicate that Isectolophus had a 

 short fore limb. 



The Carpus. The most important portion of the skeleton is the nearly complete 

 right carpus with portions of the second and third metacarpals attached. This 

 is the first carpus discovered belonging to any genus in this line of descent and 

 with the cuboid fully establishes the systematic position of Iseclolophus in the tapir 

 line, as already inferred from the peculiarities of its molar teeth. The vertical diam- 

 ctei- of the carpus proper is considerably less than the transverse, the series retaining 

 in great measure the rather spreading character of the iiriinitive type. The first and 

 second rows fully alternate and interlock. The scaphoid has a subquadrate anterior 

 face; the radial facet has a broad posterior extension. The trapezium facet is worn 

 away; the trapezoid facet is excavated and is only a trille broader than that abut- 

 ting against the magnum. The hinar has a symmeti'ical radial facet with a promi- 

 nent posterior hook; the inferior face presents subequal magnum and unciform facets, 

 with closely similar angles of inclination ; this is a very distinctive feature;. The 

 cuneiform has rather a limited transverse extension of the idnar facet, with a small 

 pisiform facet; the lunar and unciform surfaces are subequal. The trapezium is not 

 preserved, but is indicated by a wide facet upon the trapezoitl and upon mc. it. The 



