414 [OCTOBER; 



Very much resembles the common mouse. Burrows in the earth and comes 

 out at night to eat. Its food appears to consist chiefly of green vegetables. 



In the preliminary remarks to this memoir, I alluded to a species of Mus in- 

 habiting the Southern States, which might be considered as native and not im- 

 ported, which was mentioned in Audubon and Bachman's Quadrupeds as a variety 

 of Mus rattus. This animal was known many years ago to Seba, Klein and 

 Brisson, and figured or described by them. The following description of it 

 made many years ago, although some what imperfect, may help to pomt it out. 



Mus Amehicanus. Hair dark cinereous, above tipped with reddish brovv^n, 

 and dusky with many long scattering hairs of the latter color, beneath with 

 vjrhite, having a tinge of yellow particularly towards the sides. Ears rather 

 large, oval, blunt, naked. Feet whitish, covered with short hairs. Thumb tu- 

 bercle furnished with a short blunt nail. Tail terete, long, annulosely scaly, 

 furnished with short hair. 



Hah. In Georgia and Carolina. Mus Americanus Turton's Linnaeus, Vol. I, 

 p. 50. Rattus Americanus Brisson, Regne Animale, p. 172. Mus Americanus 

 Klein, Quad. p. 53. Seba, Vol. II. tab. 29, fig. 2. 



This rat was formerly very common in the midland counties of Georgia. I, 

 however, know nothing of its habits. The following measurements were taken 

 from many different specimens. Length of head and body 7.74 ; tail 7.8 ; head 

 2.05 ; ears .9. 



Mus ViRGiNiANUs. Color entirely white. Ears, feet and tail flesh color. 

 Eyes brown. Ears moderate, blunt, naked. Feet thinly covered with short 

 hair; thumb-tubercle with a short blunt nail. Tail thick, rather blunt, quad- 

 rangular, the upper side convex, the others plane, annulosely scaley, with short 

 hairs proceeding from the base of the rings. 



Hab. In Texas. 



Length h. and b. 7.3 ; tail 6.2; diameter at root .3, at point .2. 



Mus Virginianus Turton, 1. c., p. 82. Mus albus virginianus Brisson, 1. c, 

 p. 173. M. agrestis virginianus Klein, 1. c, p. 57. Seba, Vol. I., tab. 49, fig. 4. 

 Virginian rat Pennant. Art. ZooL, Vol. I., p. 32. 



In the year 1840, a ship arrived at New York, from Tampico, which was over- 

 run with rats of this species ; a number of them were given to Mr. J. J. Audubon, 

 who made a drawing of the animal and kindly gave me one, from which the 

 above description was made ; it is not as full and perfect as it might be, as I had 

 no thought at the time of ever publishing it. The cranium differed in many respects 

 from that of the M. decumanus, to whichit appeared evidently allied, althougn 

 the tail was so different. I shall close these observations with a few remarks 

 on some other Rodentia. 



Neotoma FLORiDANUM. Is by no means confined to the southern states, three 

 individuals having been taken by Mr. Bell, of New York, near Nyack, on the 

 western bank of the Hudson river, about twenty miles above the city. One of 

 these was considerably larger than any I had ever seen, the head and body mea- 

 sured 11 inches, the tail 7.5. 



This animal was first described by Mr. Ord, in the Bulletin of the Societe 

 Philomathique de Paris, in the year 1818, under the name of Mus floridanus, and 

 afterwards in the Journal of the Academy of Natural Sciences, of this city, as 

 Neotoma floridana. Harlan arranged it under the genus Arvicola, from which it 

 differs very much in its dentition, as well as in other respects. It is the Ameri- 

 can rat of Pennant, Arct. Zool., vol. i., p. 130, w^here he confounds it with a 

 Siberian animal described by Pallas. 



SiGMODON HispiDUS. This animal is subject to considerable variation in the 

 rniJdle molar of both jaws, which has usually but one external and one internal 

 enamel fold on each side, sometimes, however, there are two external folds, the 

 additional one being anterior and smaller. 



We are indebted to Mr. Ord for the first published notice of this rat, which 



