MAMMALS OP THE MEXICAN BODNDAET. 



455 



The following comparative measurements indicate the average size of the three forms 

 (measurements in millimeters): 



oCf. Chapman, idem., p. 44. 



This is doubtless the large pale form mentioned by Doctor Coues (Mon. N. Am. Eoden. 

 1877, p. 116) as occurring at Neosho Falls, Kansas. All erf the Oryzomys thus far examined 

 from Brownsville, Texas, have proved to be 0. aqvaticus — a very different species from any 

 form of the 0. palustris group. On the other hand. Corpus Christi Chapman, 1. u., p. 45) 

 and Rockport specimens have all proved referable to what is here termed 0. p. texensis. 



The Rockport series numbers 29 specimens, and includes young of various ages, middle- 

 aged specimens, and eight or ten that are fully adult. Two were taken in March, one in 

 January, and the rest between October 4 and December 5. One (No. 65, Coll. H. P. Att- 

 water) is exceptionally rufescent. This is the single example mentioned by Mr. Chapman 

 (1. c, p. 45) as apparently referable to his 0. p. natator. (Bull. Am. Mus. Nat. Hist., VI, 

 1894, p. 276.) 



The Texas form is probably subspeciflcalty distinct from Oryzomys 

 palustris. I have recently compared a series of topotypes of palustris 

 from New Jersey with series from Virginia and South Carolina, the 

 latter practically topotypes of Arvicola oryzivora Bachman ( = Ory- 

 zomys palustris oryzivorus, Rhoads)'*, and find the northern form to be 

 distinguishable from the others by its smaller ears (almost as small as 

 those of natator from Florida), more grizzled pelage above and below, 

 slightly shorter tail, and more robust skull. If not the subspecies tex- 

 ensis, the Ricefield mouse of Texas must be called Oryzomys palustris 

 oryzivorus (Bachman). 



ORYZOMYS AQUATICUS Allen. 

 AIIEN MCEFIELD MOUSE, 



Oryzomys aqvaticus Allen, Bull. Am. Mus. Nat. Hist., HI, p. 289, June 30; 189t 

 (original description). — Meeeiam, Proc. Washington Acad. Sci., HI, p. 277, July 

 26, 1901 (Synopsis of the Rice Rats [genus Oryzomys] of the United States and 

 Mexico). — MiLLEE and Rehn, Proc. Bost. Soc. Nat. Hist., XXX, No. 1, Dec. 27 

 1901, p. 92 (Syst. Results Study N. Am. Mam. to close of 1900).— Elliot, Field 

 Col. Mus., Zool. Ser., 11, 1901, p. 146, fig. 32 (skull and teeth). 



Type-locality. — Brownsville, Cameron Countj^, Texas. 



Geographical range. — Subtropical zone, in the Tamaulipan Tract 

 southeastern Texas. 



Description. — Size large; tail long; upper parts yellowish brown; 

 under parts buff; tail brown above, yellowish below. Total leno-th 

 290 mm.; tail vertebrae, 150; hindfoot,33. Skull massive, high inter- 



oAmerican Naturalist, XXXVI, No. 428, August, 1902, p. 662. 



