Previous to this report only one subspecies of _Oryzomys palustris_ had
been recorded from Tamaulipas. Careful examination of the available
material from the state shows that _O. p. aquaticus_ occurs in the east
and _O. p. peragrus_ lives in the southwestern part of the state.
In general, specimens examined were trapped in dense brush alongside
waterholes as at Altamira, or around cornfields as at the place 36
kilometers north and 10 kilometers west of Ciudad Victoria, where the
bushes were mesquite and other kinds of Acacias. There the ground was
covered by cat claw, and no grass was seen near the traps in which _O.
palustris_ was caught. In the Sierra de Tamaulipas a specimen was
caught among rocks and bushes. Ingles (1959:395) reported that his
specimens were trapped alive in dense brush and "tules."
A female taken at Jaumave on July 25 had 5 embryos, each 20 mm. in
crown-rump length.
=Oryzomys palustris aquaticus= J. A. Allen
1891. _Oryzomys aquaticus_ J. A. Allen, Bull. Amer. Mus.
Nat. Hist., 3:289, June 30, type from Brownsville, Cameron
Co., Texas.
1918. _Oryzomys couesi aquaticus_, Goldman, N. Amer. Fauna,
43:39, September 23.
1960. _Oryzomys palustris aquaticus_, Hall, The Southwestern
Nat., 5:173, November 1.
_Distribution in Tamaulipas._--North part of state, and
coastal area south to Tampico.
Weights of two males were 80 and 82, and of a female 66 grams.
_Oryzomys palustris aquaticus_ differs from _O. p. peragrus_ in having
a rich cinnamon, reddish color and the interorbital region constricted
to less than 14.7 per cent of the greatest length of the skull. _O. p.
peragrus_ is ochraceous and grayish. The least width of its
interorbital region is more than 14.5 per cent of the greatest length
of the skull. Individuals studied from the Sierra de Tamaulipas are
typical _aquaticus_. Of those from Altamira, one has the color as in
_aquaticus_, but the color of the other two resembles that of
_peragrus_; nevertheless, all of the mentioned specimens are here
assigned to _aquaticus_.
_Records of occurrence._--Specimens examined, 4: Sierra de
Tamaulipas, 10 mi. W, 2 mi. S Piedra, 1200 ft., 1; 6 mi. N,
6 mi. W Altamira, 2; 5 mi. N, 5 mi. W Altamira, 1.
Additional records: Camargo (Goldman, 1918:40); Matamoros
(_ibid._); near Cd. Tampico (Ingles, 1958:395).
=Oryzomys palustris peragrus= Merriam
1901. _Oryzomys mexicanus peragrus_ Merriam, Proc.
Washington Acad. Sci., 3:283, July 26, type from Rio Verde,
San Luis Potosi.
1918. _Oryzomys couesi peragrus_, Goldman, N. Amer. Fauna,
43:39, September 23.
1960. _Oryzomys palustris peragrus_, Hall, The Southwestern
Nat., 5:173, November 1.
_Distribution in Tamaulipas._--Western part of state, along
Sierra Madre Oriental.
Two males from Jaumave weighed 62 and 65 and one pregnant female
weighed 67 grams.
Most records of _O. p. peragrus_ are from places along the Sierra Madre
Oriental, but Lawrence (1947:103) recorded a specimen from the Rio
Corona, which is east of, but not far from the mentioned Sierra. Baker
(1951:215) reported two specimens from two different localities labeled
with reference to Ciudad Victoria (same specimens reported here) as _O.
p. aquaticus_, but pointed out that they tended "toward the darker _O.
c. peragrus_." Examination of more material and taking into
consideration the relation between the interorbital constriction and
the greatest length of skull, cause me here to refer those specimens to
_peragrus_.
Hooper (1953:8) reported three young specimens from Rancho Pano Ayuctle
as of the subspecies _aquaticus_, but study of two adults from the same
locality reveals that this locality should be included within the
geographic range of _peragrus_.
_Records of occurrence._--Specimens examined, 9: 36 km. N,
10 km. W Cd. Victoria, 1; Jaumave, 2400 ft., 5; Rancho Pano
Ayuctle, 25 mi. N, 3 km. W El Mante, 2; 70 km. S Cd.
Victoria (by highway) and 6 km. W of Highway, 1.
Additional records: Rio Corana (Lawrence, 1947:103); Pano
Ayuctle (Hooper, 1953:8).
=Oryzomys melanotis=