he same as they are
in _D. o. compactus_ of Padre Island.

_Specimens examined._--Total, 11, all from Texas. Aransas County:
Mustang Island, 14 mi. SW Port Aransas.

Sigmodon hispidus solus new subspecies

Hispid Cotton Rat

_Type._--Male, adult, skull and skin; No. 35468, Mus. Nat. Hist., Univ.
Kansas; from island, 88 mi. S and 10 mi. W Matamoros, Tamaulipas,
Mexico; 22 March 1950; obtained by E.R. Hall and Curt von Wedel;
original No. 6806 E.R. Hall.

_Range._--Known from the type locality only but probably occurring on
most of the chain of islands off the coast of Tamaulipas.

_Diagnosis._--Small; hind foot short; rostrum broad.

_Comparison._--From its nearest relative, geographically and
morphologically, _Sigmodon hispidus berlandieri_ Baird of the adjacent
mainland, _S. h. solus_ differs in smaller size, and a rostrum that is
broader in relation to the length of the skull.

_Remarks._--On the last night of our stay on the island, traps set in
grass approximately 20 inches high, yielded one pair of _Sigmodon_. The
color is lighter than in the average of specimens from the mainland (for
instance those from Victoria and Soto la Marina) but can be matched by
selected specimens. In animals of equal age, the hind foot and basilar
length are shorter in _S. h. solus_ than in _berlandieri_. The
broadening of the rostrum, which occurs with advanced age, is attained
in _solus_ when the skull is yet short; the maximum breadth of the
rostrum in the adults is more, instead of less, than a fourth of the
basilar length.

_Measurements._--The following measurements are of specimens in which
the occlusal face of each molar tooth is worn flat. The first
measurement is of the holotype followed by the corresponding measurement
of a male of _T. b. berlandieri_, No. 116466 from Camargo, Tamaulipas,
in parentheses. The third measurement is that of the female from the
type locality of _S. h. solus_ and it is followed by the corresponding
measurement of a female of _T. b. berlandieri_, No. 116462 from Camargo,
Tamaulipas. Total length, 266 (298),--(293); length of tail, 113
(135),--(137); length of head and body, 153 (163), 155 (156); length of
hind foot, 30 (35), 30 (33); basilar length of Hensel, 28.2 (28.9); 27.9
(29.0); zygomatic breadth, 19.5 (--), 19.0 (20.8); mastoidal breadth,
13.9 (14.4), 13.9 (14.8); greatest breadth of rostrum, 7.2 (7.3), 7.8
(7.2); length of nasals, 14.6 (14.1), 13.4 (14.2); crown length of upper