-[popular SBtrttomm) of mmatclr $ature. 461 



only at the place struck, but at two or three I terior compressed molars, and four sharply 

 other places ; the muscles being articulated tubereulated back molars, the superior of 

 in a singular manner, quite through to the which are triangular, the inferior oblong : 



vertebrae. Hence this reptile has obtained 

 the name of the Glass Snake. 



OPHIDIA. The name given to an order 

 of Reptiles which includes the Serpent 

 tribes. The species belonging to this order 

 may be naturally grouped in three sec- 

 tions:!. Harmless Snakes; 2. Venom- 

 ous Snakes ; IS. Water Snakes. The Harm- 

 less Snakes arc divided into two families, 

 the (Jolubriilie and the fMdue : many of them 

 being very large, and possessed of enormous 

 muscular strength. The Section of Venom- 

 ous Snakes also contains two families, the 

 Crnf"li,/n'. t or Rattle-snakes, and the Vi- 

 la riiln , <>r Vipers. The Water Snakes belong 

 to the family J/i/rlriilti; and are character- 

 ized by the compressed form of their bodies, 

 and by the vertical flattening of the tail, 

 which enables them to swim with facility. 

 [See SKIU-KNTS : SNAKES : BOA CONSTKIC- 

 TOH : RATTLE-SNAKE : VITEK, &c. 



OPHIDIUM. There are three or four 



species offish bearing this name ; all small 

 and anguilifonn. One, called the BKAKUKD 

 Ornimu.M, is about eight or ten inches in 

 length, and has two long bifid cirri or bar- 

 bulcs beneath the chin. It is found in the 

 Mediterranean sea, and is in great plenty in 

 the Adriatic. It feeds upon small crabs 

 and fishes, but the flesh is considered rather 

 coarse. The BEAHIJJ.KSS Ormuii-M is only 

 about three inches long ; the head is very 

 obtuse, and the body is ensiform, consider- 

 ably compressed towards the tail. 



OPUIOPS. A genus of Lizards, princi- 

 pally distinguished by the absence of eye- 

 lids. Ophinps eleyans, a species found in 

 Smyrna, is of an olive colour above : two 

 yellowish lines extend along each side of 

 the trunk ; each of these lines separates two 

 rows of black spots, which are small and 

 very distinct when the reptile is young, but 

 more or less dilated and confused in adults : 

 they are white beneath. 



OPIIIURA. Lamarck's name for a genus 

 of Star-fishes. 



OPOSSUM. (DideJphis.) The name of a 

 family of marsupial quadrupeds (of the genus 

 Didelpliu), peculiar to the American coiUi- 

 ncnt ; and of which about twenty species are 

 known ) some of them being scarcely larger 



OPO8S O M. (UIDEI.PBIS CANOBlVORAt) 



a mouse. They are characterized by 

 number of the incisor teeth, which 

 are ten above and eight below ; three an- 



tlmn 

 the 



so that, with the four canines, they have in 

 all fifty teeth, a number greater than has as 

 yet been observed in any other quadruped, 

 except the newly-discovered 3fyi-mccobius. 

 The limbs are short ; the feet plantigrade ; 

 and the toes, which are five on each foot, 

 armed with sharp, strong, curved claws, 

 except the inner toe or thumb on the hinder 

 firt, which is opposnble and destitute of a 

 nail. The tail is scaly and naked, except 

 at its base ; and is usually more or less pre- 

 hensile. In some of the smaller species 

 the pouch is almost entirely wanting, being 

 indicated only by a slight fold of skin ; and 

 in these the young adhere to the mother by 

 entwining their little prehensile tails around 

 hers, clinging to the fur of her back. 



When, on the discovery of the Western 

 Continent, this singular genus first became 

 known, this hitherto unheard-of contrivance 

 of nature for the protection and preservation 

 of the young justly excited the admiration 

 of naturalists ; nor can any one, indeed, 

 who for the first time witnesses this mar- 

 supial wonder, withhold the expressions or 

 conceal the signs of his astonishment. 



The VIRGINIAN OPOSSUM (Dklclphis Vir- 

 aitiidmi), being one of the largest and most 

 robust of the genus, and at the same time 

 common in many parts of the southern 

 states of North America, we shall take it as 

 the best species to describe. This animal is 

 about the si/.e of a cat, but appears thicker 

 cwing to the length and upright growth o< 

 the fur. It has a long sharpened face, and 

 very wide mouth, armed with numerous 



sharp teeth ; the ears are thin, naked, round, 

 and blackish, edged with a border of white : 

 the legs arc short : the feet armed with short 

 claws, but the interior toes of the hind feet 

 are flat and rounded. The whole hair is of 

 a wool-like softness, short on the face and 

 body, but long on the legs ; and the general 

 colour is a light gray. The tail is thick and 

 black for upwards of three inches at the 

 base, and is covered with small scales. The 

 Opossum is a nocturnal and timid animal, 

 residing in the day-time in the hollows of 

 trees, or among the branches, and prowling 

 at night in search of its food, which consists 

 of insects, eggs, birds, small reptiles, &c., as 

 also fruits and roots ; sometimes even in- 

 vading the precincts of the farm-house, and 

 killing the poultry. Its movements on the 

 ground are slow and awkward ; but it climbs 

 trees with great facility, and uses its pre- 

 hensile tail with great elfect in suspending 



