Diagnosis.—Size small (see measurements). Color dark, entire dorsal surface (c) between Pinkish Buff and Cinnamon-Buff, purest on sides and flanks, upper parts mixed with black; arietiform markings, pinnae of ears, dorsal and ventral stripes of tail, plantar surfaces of hindfeet, brownish-black. Skull small; auditory bullae but slightly inflated in relation to size of skull; nasals slightly flaring distally; premaxillae extending but slightly posterior to nasals; interorbital width relatively great; external auditory meatus small; rostrum relatively long and wide; zygomatic arches relatively heavy.
Comparisons.—From Dipodomys ordii ordii, D. o. sennetti differs in: Size smaller, tail shorter; color darker; skull smaller; nasals longer; rostrum wider; auditory bullae less inflated; external auditory meatus smaller; pterygoid fossae more rounded; zygomatic arches heavier.
From Dipodomys ordii medius, D. o. sennetti differs as follows: Size smaller; color darker, but with less red in pelage; skull markedly smaller in all respects.
From Dipodomys ordii compactus, D. o. sennetti differs in: Size somewhat less; color darker; skull with total length greater; orbit smaller; least interorbital width greater; braincase more inflated; width across auditory bullae more; interparietal region wider; external auditory meatus larger; medial part of audital portion (see [Howell], 1932) of auditory bullae larger.
Remarks.—Dipodomys sennetti, along with Dipodomys compactus, was regarded by [Davis] as conspecific with Dipodomys ordii. Reasons for placing these two kinds of kangaroo rats as subspecies of D. ordii are given in the account of Dipodomys ordii compactus.
This subspecies is known only from north of the Rio Grande which may serve as a barrier to the spread of the animal into northern Tamaulipas.
Specimens examined.—Total, 20, all from Texas, distributed as follows: Atascosa County: Somerset, 2 (TCWC). LaSalle County: 8 mi. NE Los Angeles, 1 (TCWC); 8 mi. E Encinal, 1 (TCWC). Kleberg County: 2 mi. S Riviera, 9 (TCWC). Jim Hogg County: Hebronville, 8 (LACM). Brooks County: Falfurrias, 2 (LACM). Willacy County: 28 mi. E Raymondville, 2 (TCWC).
Dipodomys ordii evexus [Goldman]
Dipodomys ordii evexus [Goldman], Journ. Washington Acad. Sci., 23:468, October 15, 1933.