DIDELPHIS.
One species, referred to this genus, has been found by Cuvier in the vicinity of Paris; and as it will interest and instruct the reader of this article, to see by what means this indefatigable and acute naturalist was enabled to effect his purposes, and what was the kind of reason ing he followed in these investigations, we shall give a sketch of his proceedings with respect to it, as well as to some of the more obscure and difficult species mentioned in this catalogue.
He remarks, that the quantity of bones imbedded in the gypseous strata of Paris is such as to be scarcely credi ble. As in many of these there is scarcely a block that does not inclose a bone, he observes, that millions must have been 'destroyed by the immense excavations former ly made, before these objects had begun to attract atten tion. Many are lost every day, either from the difficulty of extracting them, from their minuteness and their fra gility, and from the carelessness of the workmen ; and yet, in spite of all these obstructions, an almost incredible number of species has been ascertained.
It was in the midst of these random researches that he discovered a skeleton of small size in two pieces of gyp sum. By dissecting these carefully, he was enabled to make out the parts so distinctly, as to ascertain that it be longed to an animal of the family of Pedimanes, which are distinguished by having a separated toe on the hind foot, and a pouch under the abdomen. These animals were disposed into thirteen species in the genus Didel phis; but Cuvier divides them into the three following genera, or sub-genera, as he considers that arrangement objectionable.
I. Sarigue. With ten incisors, of which the middle one is longest, in the upper jaw, and eight in the lower; the canine teeth are long and pointed, and the tail is pre hensile. This division contains the Didelphis marsu pialis, carcinophaga, virginiana, opossum, murina, dorsigera, brachiura, and minima.
2. Dasyure. With eight incisors above and six below. The tail is furnished with long hair, and is not prehensile. This contains only the Didelphis maculata.
3. Phalanger. This has six incisors above and two long ones below, directed horizontally forwards. There are three or four canine teeth below, hardly passing through the gums, and the second and third toes of the 'hind feet, sometimes even the fourth, are joined together to the claw. This division contains the Didelphis ori
entalis and volans. The kangaroo is separated from the. Didelphis by the name of Macropus.
From the elevation of the coronoid apophysis of the condyle, and the sharp projection formed by the posterior angle of the lower jaw, M. Cuvier drew the first inference that the skeleton under his hands had belonged to the order of carnivorous animals. From the elevation of the condyle far above the horizontal line on which the teeth are placed, it was then inferred that it did not belong to those carnivorous animals which have teeth provided with a cutting edge, such as the dog, cat, weasel, and badger. Hence it became included among the small Pedimanes, or generally among the insectivorous animals.
The hedge-hog, the mole, the shrew, and some bats, have the condyles placed in the same manner, as well as the Didelphis. But the skeleton was determined to be long to the latter, from the great height and width of the coronoidal apophysis. In the mole it is wide, but lower, and placed in a different direction. In the Didelphis murina the breadth was the same, but the height less. Here it seemed to approach to the hedge-hog, as it also did in the sharp projection of the angle of the jaw. But in the Didelphis that projection bends inwards, together with all the inferior edge of this part of the jaw, and this very characteristic circumstance was discovered in the skeleton.
The examination of the teeth confirmed that which was taught by the appearances of the jaw, as they possessed the general characters of those of the insectivorous ani mals, which are proper to the Pedimanes, and most par ticularly to the Sarigues. That character is, to have pointed tubercles, without either a flat crown or cutting edges. After carefully comparing the teeth of the fossil jaw with those of the other Pedimanes, he found that they agreed with those of the Dasyure, with the New Holland animals that belong to Didelphis, and that have a hairy tail which is not prehensile, and with the common Sarigue of America. To which of all these it was to be referred could not be determined from these parts.