RODENTIA.
Measurements of Hhizomys pruinosus.
9
Inches. Inches
Muzzle to vent .
Length of tail . . . . . . . . . . , . . 1 ,
„ of fore foot. . . . . . . . . . . .
„ of first toe . . . . . . . . . . . .
„ of middle fin g e r....................................... .
„ o f hind f o o t .....................................................................
„ of first toe . . . . . . . . .
„ of middle toe . . . . . . . . . . . . .
Eye to eye, inner angle (callipers) . . . . . . . 1-18 . 1-00
„ to ear ( c a l l ip e r s ) ................................................................................................... 1-20 1-10
Ear to ear (callipers) ..................................................................... . . 2-00 1-70
The skull of JR. pruinosus, Blyth (see Plate XVI, figs. 1—3), is very distinct from
that of R . badius, Hodg., from which it is distinguished by its much greater size and
by the flattening and expansion of the frontal region behind the nasals and by the
backward prolongation of the ridges from the external orbital angle of the frontal
which form nearly one-half of the upper and inner margin of the zygomatic fossa,
while in JR. badius, Hodg., these ridges being directed inwards to the middle Imp.
unite immediately behind the nasal bones. In JR. pruinosus, Blyth, the premaxillaries
do not extend behind these bones, while in JR. badius, Hodg., they do, and almost
embrace their hinder extremities. The frontal contraction also of JR. prumosus,
Blyth, is situated much farther back than in JR. badius, Hodg., so that the posterior
division of the brain-case is much more truncated than in the latter species. The
zygomatic arch also is more rounded and outwardly projected in the latter. In
JR. prumosus, Blyth, the surface of the palate, immediately behind the premaxillary
foramina, is broad and rather deeply excavated, the concavity being laterally defined
by two well marked ridges, while in R . badius, Hodg., there is no such concavity,
the mesial line being occupied by the elevated and rounded margins of the
palatine surfaces of the maxillae. The palatine surfaces of the palatines of R.
pruinosus, Blyth, are flat, and expanded, and on the same plane with the similar
surface of the premaxillaries the mesial line of union of which is not marked by any
median ridge, whereas in R. badius, Hodg., the palatine surface of the maxillaries is
rather deeply concave from side to side, and the mesial line is occupied by a ridge,
the same aspect of the palatines being considerably reduced, much transversely
concave, and sloped upwards and backwards, the wings of the sphenoid being considerably
less divergent than in R. prumosus, Blyth. These differences at once
suffice to separate R. badius, Hodg., and R. minor, Gray, from R. .prumosus, Blyth,
and they confer an altogether different conformation on the opening of the posterior
nares to that which distinguishes R. pruinosus, Blyth, in which the palatine margin
is broad and transverse, while in these two other species it is narrow and arched.
The nearest ally of the skull of R . prumosus, Blyth, would appear to be the skull of
R. sinensis, Gray, which has the flattened palate and the expanded frontal region of
this species, but differs from it in its narrower palate, shorter and broader muzzle,
and in the ridges from the external angle of the frontal being divergent from each
other as far back as the occipital ridge, whilst in R. pruinosus they are confluent
at the anterior extremity of the parietals. I t differs from R . sumatrensis, Raffles,
in its less expanded frontal region, in the greater contraction of the frontoparietal
area, which is much further forward than in that species, and the much
narrower and less massive character of the skull. In R. sumatrensis, Raffles, the
greatest breadth across the zygomatic arch considerably exceeds the distance between
the anterior border of the premaxillaries and the hinder margin of the articular
surface for the lower jaw, whilst in R. pruinosus, Blyth, it may fall short of that
interval, but never exceeds it. The area behind the premaxillary foramina is
much more concave than in R. sumatrensis, Raffles, and the palate of that
species is concave and the posterior nares more expanded, but the palatine is
in the same plane with the maxillaries. The nasals in R. sumatrensis are pointed
posteriorly, with the maxiUo-premaxillary suture some distance anterior to the
extremities, and they are much more laterally expanded than in R. prumosus, Blyth,
and the sides of the osseous muzzle of the former are vertical from a ridge external
to the nasals, whereas in R. prumosus the ridge is absent, and the sides of the
muzzle are convex. In these latter details regarding the muzzle, R. badius, Hodg.,
R. minor, Gray, and R. sinensis, Gray, agree more with this species than with
R. sumatrensis. The alveolar border is longer in R. prumosus than in the latter,
and the teeth are larger.
This species does not appear to attain to the same size as R. sumatrensis, Raffles,
but it greatly exceeds the dimensions of R . badius, and of course is greatly larger
than R. minor, Gray.
Measurements of skulls of S and ? R. pruinosus, Blyth, and R. badius,
Hodgson:—
B.prtanonu fi. badiut.
9
Inches. Inches.
Length, from inferior margin of foramen magnum to tip of premasillte 2-60 2-62 1-85
Greatest breadth across zygomatic arch . . . . . . . . . 1-97 2-00
Breadth of muzzle at anterior margin o f lower border of infraorbital foramen 0-63 0-64
„ across frontals at external orbital a n g le ..................................................................... 0-83 0-78
„ „ frontal contraction ...............................................................................
„ „ inner borders of infraorbital foramina ................................................. 0-51 0-51
„ between upper borders of auditory o p e n in g ........................................................... 1-22 1-22 1-03
Length of palate, posterior surfaces of in c is o r s ..................................................................... 1-46 1-49 1-14
„ of alveolar border, outer margin 1st to 3rd m o l a r ................................................. 0-53 055
Breadth of palate between inner margins o f 2nd m o l a r s ................................................. 0-17 0:19 0-20
„ between paroccipital p r o c e s s e s ............................................................................... 0-87 0-81 1 066
Greatest breadth aoross posterior aspect of sk u ll..................................................................... 1-30 1-29 0-94
R h iz o m y s m in o r , Gray. Plates XV & XVI.
Rhizomys minor, Gray, Ann. and Mag. Nat. Hist. 1842 vol. x., p. 266.
Rhizomys minor, Horsfield, Cat. Mamm. E. Ind. Co/s Mus. 1851, p. 165.
Rhizomys minor, Schinz, Syn. Mamm. 1845 vol. ii., p. 126.