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Show 24 ZOOLOGY OF TilE VOYAGE OF THE BEAGLE. segment of a larger circle than the inner one, whilst in L. Platensis both portion are equal. The principal difference in the dentition of the La Plata and the Chile otters, consists in the comparatively smaller size of the posterior molars, both of the upper and lower jaws, of the latter species. In the upper jaw, the "carnnssiere" has its inner lobe, approaching somewhat to a triangular form, whereas in L. Platensis it is broader and almost semicircular. In the lower jaw, tbe last molar but one has the innm· lobe much smaller than the middle outer lobe, whilst in L . Platensis these two lobes are of nearly equal size and elevation. Other points of dissimilarity will be perceived in the annexed table of admeasurements. \\Thole I ngtl• of skull . Greatest width \Yitlth of skull from the apex of one mastoid process to the opposite . Length of pahtte . Breadth of pahte between tho posterior molars , Length from last molr~r to posterior nmrgin of palate . from hasc of canine to hinder part of last molar of carnassicro Width of clo. Length of htst mohr Width of do. Leugth of mmu. of lower j :tw from canine to hinder portion of last mohr (lower jaw) of h st molar Lut one (lower jt~w) Width of do. L. Chilensis. In. Lines. a 9 ~ 2 6~ 2 at 6 7* 3!J 11§ 5 5 2 ~ 4b 2 1·~ 2~ 5 ~ 2~ L. Platensis. ln. Lines. 4 2~ 2 10 ~ 2 Sk 1 10 2 7f 51 1 II 5¥. 6} 31 53 8 ~ 4 4L 4 65 3 ~ "'fhese animals arc exceedingly common amongst the innumerable channels and bays, which form the Chonos Archipelago. They may generally be seen quietly swimming, with their heads just out of water, amidst the great entangled beds of kelp, which abound on this coast. They burrow in the ground, within the forest, just above the rocky shore, and I was told, that they sometimes roam about the woods. This otter docs not, by any means, live exclusively on fish. One was shot whilst running to its hole with a large volute-shell in its mouth; another (I believe the same species) was seen in Tierra del Fuego devouring a cuttle fi h. But in the Chonos Archipelago, perhaps the chief food of this animal, as well as of the immense herds of great seals, and Hocks of torus and cormorants, is a red coloured crab (belonO'inO' to the family Macrouri) of the S.i ze o f' a prawn, which swims near the bs urbf ace in such dense bodies, that the wate1· appears of a red colour. This specimen weighed nine pounds and a half."-D. |