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Show 60 ZOOLOGY OF TilE \OY.AGE OF THE BEAGLE. xtent of the ympltysis menti. In the form of the inci ors, the more contract d palate, the great extent of the symphysis menti, and in fact in most of the points of di imilarit • bet\"een the kull of the pre ent animal and that of illus dewmanus, here p;inted out, it will be perceived, there is an approach made to the Arvicol idm. The dimen ion of the kull (so far as an imperfect specimen will allow of their being taken) are a follows:- Di,tancc between front of inci ors (upper jaw) and the fir t molar tooth Longitudinal extent of the three molars on either side, taken tggctber L!!ngth of na.,al bones --of inci~i ,.e j o1·amina . Width between oruit Length of ramus of lower jaw In Lines. 0 0 0 0 4~ 7 ~- 4!, 2~ 1.\ Fig. 3, c, Plate 33, represents tbe molar teeth of the upper jaw. Fig. 3, d, tho e of the upper jaw. " Thi rat was caught at Bahia Blanca where the plains of Patagonia begin to blend into the more ~ rtile rerrion of the Pampa . It lived in holes among t the tussocks of ru hcs, on the bon.lers of a small, still, brook; in it manner of diving and aquatic habit' it clos ly re em bled the English water-rat, (An:icola nmpltibia. )"-D. When at Paris I examined what 1 believe to be the original flius Bra::iliensi , ince the pecimen was lab lied "Rat de Bra::.il St. Hilaire, 1818." It a!ITees perfectly with the pre ent animal excepting in being rather smaller, the length from the nose to the tail being 7 inches and 4 lines-the length of the tail i 7 inche 9 line , and that of the tar us is l inch 11 Jines; this difference in the lenath of the body may ari e from differcn<'e of age, or even of sex. In the Pari :\[u eum I saw what appeared to me to be a variety of the same species in which the under parts of the body are white. I have been minute in my description of the Jlfus Braziliensis, since it i confound d by Dcsmare t, Fischer and Les on with the Rat troisieme or Rat Angouya of Azara, which I believe to be a very different animal. The de cription aiven by the author just mentioned are taken from Azara, who give the following characters to di tinguish the Rat Angou a : " Du museau ala queue, et sur le cote du corps tout e t brun-cannelle, parceque les poils ont une petite pointe cannelle; pui , ils sont ob curs et enfin blanc vers las peau. Toutc la partie infcrieure de \'animal e t blanchatre, plus claire sous Ia tete, et plus foncee entre les jamhes de devant; le pelage e t doux, tr s-serre, et le poil, qui est ala racine de l'oreille, cache le conduit de ce\le-ci. |