MAMMALS. 



43 



" The people of tlie neighborhood of Fort Duncan talk of a three years' cyduF, during which the appearance of hundred 

 thousands of rats is repeated once. According to the description given to me, I think the animal to be of the species above 

 mentioned. 



** Some of the soldiers who had been engaged in making the excavations for the groundworks of some of the buildings durintr 

 one of these 'rat years' told me that they could easily kill every morning from thirty to forty of these rats, which had descended 

 or tumbled down into these diggings without being able to scale again the vertical walls. 



*' According to further statements these animals seem to disappear again suddenly, after which hundreds and*"thousands can 

 be found lying dead over the surrounding table lands. The decaying matter then renders the infected atmosphere almost 

 insufferable."— (A. Schott.) 



48. KEITHEODON MEGALOTIS, Baird. (p. 451 ) 



Sp. Ch. — Largest of North American species. Head and body from 2.50 to 3 niches ; tail about two-tenths shorter. Ilind 

 foot near .70. Ears large, moderately clothed with hair. Above mouse gray, lined with darker, and tinged with rusty ; on the 

 rump and sides a fulvous wash. Beneath soiled yellowish white. 



Two specimens of Beithrodon were collected by Dr. Kennerly "between Janos, Sonora, and San 

 Luis spring, wliich I cannot readily refer to any of the described Nortli American species. In 

 size they exceed any of their congeners in tlie United States^ being nearly as large as a 



Hesperomys. The ears are conspicuously large and broad, projecting far beyond the fur. They 

 are not so thick as in li. monfanuSy and not quite so thickly clothed witli hair; more so than 

 in It. lecontii. The hind feet are moderately long ; soles hairy to the first tubercles. The tail 

 is about as long as the body, exclusive of the head ; it is well clothed with hairs, concealing 

 the annuli. 



The upper parts are somewhat of a mouse color, lined with darker, and with a rusty tinge on 

 the rump and sides ; this is tinged with fulvous. The under parts and feet are of a soiled 

 yellowish white. This animal has a much shorter tail than the California species. The ears 

 are considerably larger than in i2. montanus and lecontiu 



1039. Janos to San Luis spring. Mounted. Dr. Kennerly. 



49. HESPEROMYS TEXANUS, Woodhouse. (p. 464.) 



This species is so closely allied to the H. leucopus as to be distinguished with difficulty. 



?145, El Paso, Texas. Col. Graham. Skin. J. H. Clark.— 1037. Turkey creek, Texas 

 Nov., 1854. Major Emory. Dr. C. B. Kennerly. ^ — 579. Charco Escoudido, Mex. Lieut 

 Couch. Skin. 



" In passing through a groove of live oaks {Cln^rcus virtiis) in the valley of Turkey creek, late in the afternoon, we ohscrved 

 near the top of one of the trees a nest built of leaves closely resembling those sometimei constructed by the common Carolina 

 squirrel. Being desirous of ascertaining whether there was any animal in the nest we discharged our rifle at it, which resulted 

 in the two mice presented being dislodged from it. We knew of no reason why, in tliis locality, they should have abandoned 

 the usual hahits of their kind, and selected this position instead of building their nest in the ground, under stones, or in old 

 logs."— (Dr. Kennerly.) 



50. HESPEROMYS SONORIENSIS, Leconte, (p. 474.) 

 144. Santa Cruz, Sonora. 1851. J. H. Clark.— 9. El Paso, Texas. J. H. Clark. 



"This animal seems to live, as circumstancf'*^ may determine, either in the ground or in the hollows of trees. A specimen 

 obtained from a * hollow' of a cotton wood tree had a snug bed made r^f the fine filaments or inside bark ; in this there was aj^par- 

 ently no provision made for a family, or even for a companion. This seclusion is not probably peculiar to the genus but only 

 the freak of a disgusted or aelfinh individual. 



