454 BULLETIN 56, UNITED STATES NATIONAL MUSEUM. 



Genus ORYZOMYS Balrd (1857). 

 Oryzomys Baird, Mam. N. Am., 1857, p. 458. 



Dentition. — I. t^; M. |^=i6. 



Type. — Mus palustris Harlan. 



Characters.— Body slender; tail long, scaly, and somewhat hairy; 

 fore foot with two large oval palmar and three small rounded digital 

 tubercles; hind foot with four large rounded digital tubercles and two 

 plantar tubercles, a small rounded one near the outer side and a lai'ge 

 elongate one near the inner margin posteriorly; belly not white; 

 incisors without grooves ; molars with tubercles arranged in two longi- 

 tudinal rows; skull strongly ridged above the orbits. 



RemarJcs. — Two species of Oryzomys, 0. palustris texensis Allen and 

 0. aguaticus Allen, have been described from Texas. We did not 

 meet with them. 



ORYZOMYS PALUSTRIS TEXENSIS AUen.a 

 TEXAS RICEFIELS KOUSE. 



Oryzomys jmhistris texensis KiAJES, Bull. Am. Mus. Nat. Hist., VI, p. 177, May 31, 1894 

 (original description). — Merriam, Proc. Washington Acad. Sci., Ill, p. 276, July 26, 

 1901 (synonymy and footnote). — Miller and Rehn, Proc. Bost. Soc. Nat. Hist., 

 XXX, No. 1, Dec. 27, 1901, p. 94 (Syst. Results Study N. Am. Mam. to close 

 of 1900); XXXI, p. 84. 



[Oryzomys palustris] texensis, Elliot, Field Col. Mus., Zool. Ser., II, 1901, p. 147 

 (Synop. Mam. N. Am.). 



Type-locality. — Rockport, Arajisas County, Texas. 



Geographical range. — Southeastern Texas, in the lower AustralZone. 



Description. — The original description reads as follows: 



Above very pale yellowish gray-brown, varied with blackish over the middle of the dorsal 

 region, forming an indistinct blackish dorsal band; sides yellowish gray, very slightly varied 

 with blackish tipped hairs. Below clear grayish white, the fur plumbeous at base. 



Total length (of type, No. Jff f-, $ ad., Rockport, Texas, Nov. 15, 1893, H. P. Attwater), 

 277 mm.; head and body, 137; tail vertebrae, 140; hind foot, 30.5. 



Seven adult males give the following, based on collector's measurements taken from 

 fresh specimens: Total length, 249 to 280, averaging 264; head and body, 122 to 146, aver- 

 aging 131; tail vertebrae, 122 to 140, averaging 132; hind foot, 28.5 to 30.5, averaging 30. 



This is simply a large pallid form of the 0. palustris group. The Rockport series, when 

 compared with Louisiana and Florida specimens of 0. palustris natator Chapm.,!) is strik- 

 ingly different in coloration, about as different, and differing much in the same way, as the 

 Brown Rat {Mus decumanus) and the muskrat. The color differences are much less when 

 the Rockport series is compared with North Carolina specimens (true 0. palustris), but are 

 still very appreciable, while the size is much larger. 



o Doctor Merriam observes (Proc. Washington Academy of Sciences, III, p. 276, July 26, 

 1901): "I am unable to distinguish Allen's subspecies texensis, either externally or by the 

 skulls, from 0. palustris from Raleigh, North Carolina, and Dismal Swamp, Virginia. The 

 brain case may average a trifle narrower, but the difference is very slight." Doctor Allen 

 still regards the form as a recognizable subspecies. 



6See Bull. Am. Mus. Nat. Hist., V, p. 44, Mar. 17, 1893. 



