INiSEOTIVOEA. 
155 
four molars, of a second; a fragmentary ramus, with one molar in place; 
and some isolated molars, of a fourth individual. . 
The section near the apex of the crown of the ? superior incisor is 
lenticular, one side (?the inner) being interrupted by a low longitudinal 
ridge, from which the enamel is removed by attrition. The enamel is 
slightly and obsoletely striate. A section of the inferior incisor is oval, 
flattened on the inner side; the enamel is obsoletely rugose, and is slightly 
incurved on the upper surface near the apex. 
The grinding-face of the molars and some of the premolars is cn-shaped, 
but the anterior limb of the figure is much thickened on the inner face, so 
as to have a triangular form, the base being inward. This base is notched 
by a second groove of that side of the tooth, which interruption is oblit¬ 
erated by prolonged attrition. This portion of the crown is elevated above 
the posterior, in consequence of the more rapid removal of the latter by 
trituration. The large internal and external grooves continue nearly to the 
base of the crown, as in Ectoganus. The last inferior molar is longer 
than the others, and is three-lobed, forming by its base nearly an isosceles 
triangle. The heel is formed by the backward production of the posterior 
convexity of the co, the central line of the figure forming a diagonal ridge 
across the middle of the tooth. 
The mandibular ramus is of a deep compressed form. 
Length of three consecutive molars . : . 0.0250 
Length of the last two molars... 0. 0210 
Length of the penultimate molar... 0. 0084 
Width of the same. ^ .. 0. 0062 
Length of the last molar. . . 0. 0112 
Width of the same..... 0.0070 
Length of the incisor, second form... 0.0250 
Diameter of the same..... 0.0050 
])iameter of the incisor, first form, transverse ...... 0.0030 
Diameter of the incisor, first form, autero-posterior .. . 0. 0070 
A second specimen consists of a portion of the lower jaw, in which 
the last four molars remain. They resemble those of the specimen already 
described. The anterior one of the series assumes the form of a premolar, 
