187—10 INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
Sub-Family B .— LUTRINAE . 
According to the system adopted here, this sub-family includes only two or 
three genera, viz., Enhydris ( Enhydra ), Lutra, and perhaps Lutrictis. As all the 
specimens described here are referred to the second genus, the dental characters of 
that genus alone need be referred to. 
Genus : LUTRA, Ray. 
Including Aonyx, Barangia , Ilydrogale, Latax , Loutra , Lutronectes , Nutria ; Gray. 
Enliydriodon (AmyxodonJ, Falconer. 
Eental characters . — The only points in connection with the skeletal anatomy of the 
otters that it will be necessary to notice on this occasion are some connected with 
the dentition. Generally in the true otters the adult dental formula is as follows, 
viz., I. •§, C. j, Pm. |, M. 5 . In some forms, however [Aonyx), the first upper 
premolar is either not developed, or is shed at an early period, and the formula then 
becomes I. -§, G. \, Pm. •§, M. The molar series differs from that of more typical 
mustelines jf in the increased development of the tubercular f m. 1 ] of the upper jaw, 
and in the greater degeneration, so to speak, of the carnassier [carnassial ( pm. 4 )~|. 
The typical tubercle on the inside of the latter, instead of being limited to a small 
knob connected with the body by a narrow base, constitutes nearly half of the 
surface of the coronal [crown], and is expanded into a wide disc, bounded on its 
inner side by a sharp raised edge, occupying the whole length of the inside of the 
tooth. The outline of the carnassier is in con- 
sequence nearly triangular. The body [blade] is 
still distinctly tricuspid, as in the higher [feline] 
carnivora, but the anterior cusp is reduced to little 
more than a well-marked serrature or lobe of the 
basal ridge. The tubercular [m. 1 ] has a development 
proportionate to that of the tubercle of the carnassier. 
It is somewhat trapezoidal in the outline of its 
coronal, which is oblong in the transverse direction, 
that is considerably broader than long ; it is divided 
lengthwise by a deep hollow into two somewhat 
unequal halves, the outer and smaller of which is 
subdivided by a shallow transverse channel into two 
a raised edge ; while the inner is expanded 
into a flat disc, bounded by an edge, as in the tubercle of the carnassier, 
but it is of greater extent and more complicated in form. This arises from 
the anterior border of the coronal being raised up into a prominent 
trenchant ridge divided into two denticles, and distinct from the bounding 
Fig. 2. lutra (Aomjx) lep’omjx , Horsf. 
Upper dentition, nat. size : from a 
recent specimen in the author’s posses- 
sion, from India. The uppermost tooth 
is the tubercular (m. 1), and the tooth 
below it the carnassial (pm. 4) : pm. 1 is 
wanting. 
flattish surfaces bounded 
by 
