INSECTIVOUA. 
153 
Measurements. 
M. 
Length of the crown of the last inferior molar... 0. 012 
Width of the same anteriorly. . 0, 006 
Length between first and third cusps of the same .... 0. 006 
Depth of the ramus at the same. . 0. 020 
INSECTIVOEA. 
To this suborder I refer the genus EstJiomjx^ on account of the near 
resemblance of such parts of the dentition as are known to some of the 
genera now existing. It is not unlikely that other genera of the Eocene 
which have been referred to the Insectivora belong here. Esthonyx 
exhibits an approximation to the Tillodonta in the restriction of the enamel- 
layers of the incisors of one of the jaws to the anterior face only. The 
inferior molars have much the constitution of those of AncJiippodus, and in 
their details resemble also those of Erinaceus. As compared with the Creo- 
donta, there is a near resemblance between these teeth and the tubercular 
molars of Eidymictis, and through them to the tubercular sectorials of the 
OxycBuidce, with which they agree in essential composition. 
On the other hand, resemblances between the dentition of Esthonyx 
and the supposed Lemurine genus Tomitherium are not wanting, and the 
Rodent-like anterior teeth of the Lemuroid Chiromys suggest still further 
affinities between the Eocene members of that group and the Tillodonta. 
ESTHONYX, Cope. 
Report Yert. Foss. New Mexico, U. S. Geog. Survs. W. of 100th M., 1874, p. 6; Id., Ann. 
Report U. S. Geog. Survs. W. of 100th M., 1874, p. 118; System. Cat. Vert. 
Eocene New Mexico, U. S, Geog. Survs. W. of 100th M., 1875, p. 23. 
Incisors of two forms; the inferior subgliriform, but not growing 
from persistent pulps; the enamel covering a long and narrow external 
vertical face, and terminating above the alveolus, thus distinguishing 
crown and root. The other form of ? incisor with the apex encased in 
enamel, but extending much farther on the outer than the inner side; the 
crown compressed, not wider than the root. Molars supporting two V’s, 
with rounded apices directed outward, the posterior soon wearing into a 
triangle lower than the anterior. The anterior elevated and transverse, 
only distinguished from a triangle by a notch on the inner side. Last 
