94 MR, E. R. ALSTON ON THE GENUS aNoMALURUS. [Feb. 16, 
The spleen is of the same shape as in the Squirrels. 
The liver has the general proportions shown in the figure. The 
caudate lobe is long and pointed ; it is proportionally smaller in A. 
pelii than in A. fraseri. The Spigelian lobe is small and simple, not 
double or bifid as in almost all known rodents. There is no trace of 
a cystic notch ; and the gall-bladder lies directly over the umbilical 
fissure—an arrangement which has never been observed, as far as I 
know, in any other member of the order. 
The uterus of the female is long and double. In the male the 
penis is stated by Gervais to be provided with a bone. 
SysteMATIC Pos1TIONn. 
From the above facts it appears to be clear that the Anomalure 
is an aberrant Squirrel, with no special affinities to any other 
family, that its peculiarities are all purely adaptive, and that they 
are all in direct connexion with the functions of mastication and 
digestion. 
Thus, in the skull, if we pass the minor point of the reduction of 
the postorbital processes, we find that it is built on the true sciurine 
type, ewcept in those parts which are modified by the peculiarities of 
the masseter muscle and teeth. Mr. Waterhouse, with his usual 
acumen, remarked in his original description :—‘ The masticating 
surfaces of these teeth are worn flat by usage, even in the compara- 
tively young animal, as in other rodents which have a large ant- 
orbital opening, and have not a tubercular surface such as we find 
in the molars of the typical Squirrels. These last-mentioned 
animals, it would appear, have a rotatory motion of the lower jaw, 
while the Anomalurt have a longitudinal, no doubt combined with 
the rotatory motion; and this difference is perhaps due to the action 
of that portion of the masseter muscle which passes through the 
antorbital opening” (l.c. p. 127)*. The rest of the skeleton, save 
in the number of ribs, seems also to be that of a true Squirrel; and 
though the viscera are widely different from those of that group, yet 
they are also unlike the organs of any other family. 
The resemblances which have been pointed out to the Dormice 
and to the hystricine rodents appear to me to be merely superficial 
and adaptive. Those to the Myowide are only in the size (not the 
furm) of the infraorbital opening, and the number and general 
appearance of the grinding-teeth, and do not extend to any more 
important characters. The points of similarity to some of the 
Hystricide, in the form of the infraorbital opening, the shape of 
the bony palate, and the number of ribs, are much more striking, 
but are at once negatived by the structure of other parts, notably 
by that of the mandible, zygoma, auditory bulle, and base of tie 
skull. The teeth, which M. Gervais compares to those of Cer- 
comys, have not so great a resemblance to the teeth of any of 
the Hystricide as the dentition of the Beaver has to that of the 
widely distinct Coypu. Brandt’s comparison of Anomalurus to 
* Cf. Von Teutleben, Archiv f. Naturgeschichte, 1874, pp. 91-95. 
