r quills it is reduced to a narrow
mesial band. The stout strong quills rarely exceed six inches in
length, whilst the slender quills are one foot long. Posteriorly
above the tail and at its sides many of the short quills are pure
white. The modified quills on the tail, with dilated barb-like free
ends are not numerous, and are also white. There are three kinds of
rattle quills, the most numerous measure 0.65 inch in the length of
the dilated hollow part, having a maximum breadth of 0.21 inch,
whilst there are a few short cups 0.38 inch in length, with a breadth
of 0.17 inch, and besides these a very few more elongated and narrow
cylinders occur."--'Anat. and Zool. Res.,' p. 332.

SUB-ORDER DUPLICIDENTATA--DOUBLE-TOOTHED RODENTS.

These rodents are distinguished by the presence of two small
additional incisors behind the upper large ones. At birth there are
four such rudimentary incisors, but the outer two are shed, and
disappear at a very early age; the remaining two are immediately
behind the large middle pair, and their use is doubtful; but, as
Dallas remarks, "their presence is however of interest, as
indicating the direction in which an alliance with other forms of
mammalia more abundantly supplied with teeth is to be sought."

Another distinctive characteristic of this sub-order is the
formation of the bony palate, which is narrowed to a mere bridge
between the alveolar borders, or portions of the upper jaw in which
the grinding teeth are inserted.

The following synopsis of the sub-order is given by Mr. Alston:--

"Incisors 4/2; at birth 6/2; the outer upper incisor soon lost; the
next pair very small, placed directly behind the large middle pair;
their enamel continuous round the tooth, but much thinner behind;
skull with the optic foramina confluent, with no true alisphenoid
canal; incisive foramina usually confluent; bony palate reduced to
a bridge between the alveolar borders; fibula anchylosed to tibia
below, and articulating with the calcaneum; testes permanently
external; no vescicular glands. Two families."--'P. Z. S.' 1876, p.
97.

[Illustration: Dentition of Hare.]

There are only two families each of one existing genus--LEPORIDAE,
genus _Lepus_, the Hare; and LAGOMYIDAE, genus _Lagomys_, the Pika,
or Mouse-Hare, as Jerdon calls it. There are three fossil genera in
the first family, viz. _Palaeolagus_, a fossil hare found in the
Miocene of Dacota and Colorado, _Panolax_ from the Pliocene marl