284 REPTILIA. 



and the head plated to the eyes ; the tail terminated by a spur. Others have no subcaudal plates, and the head 

 scaled like the back. Some have the head plated, with double subcaudal plates: and others conjoin to the latter 

 character, excepting that the extremity of the tail has small scales both above and below, little scales upon the 

 head also. 



The Vipers {Vipera, Daud.), — 

 The greater number of which were confounded by Linnaeus with the Snakes proper, on account of 

 their double subcaudal plates, require to be separated from the latter by reason of their venomous 

 fangs, and grade into other Serpents with single or partly double subcaudal plates, being distinguished 

 from the. Rattlesnakes and Trigonocephalets by the absence of cavities beneath their nostrils. 



Some have only keeled and imbricated scales upon the head, like those of the back ; and others have the head 

 covered with small granulated scales, [among which is the Viper or Adder of this country]. Some again [the Ce- 

 rastes] have a pointed bone over each eyebrow, [and are peculiar to Africa]. Others, which are similar in all other 

 respects to the preceding generally, have three plates a little larger than the scales which surround them upon 

 the middle of the head. There are some Vipers, also, with plates upon the head, like those of the Common Snake. 



Naia-~h.XB Vipers with plated heads, the anterior ribs of which can be dilated and thrown forward, so as to 

 distend this part of the trunk into a disc more or less broad. The most celebrated species is the Cobra di Capella 

 of India, with a spectacle-like mark on the disk, and which is extremely venomous. The Haje, or Asp, of Egypt, 

 is another. 



Elaps. — Head plated, and an opposite organization of the body to the Asps ; their jaws even can scarcely widen, 

 on account of the shortness of the tympanic bones, and especially of the mastoids, from which it results that the 

 head is nearly of even size with the body, as in the Roles and Amphisbanes. 



Micrurus, Wagner, has merely the tail shorter. 



P/aYi/n;*, Latreille.— Head also plated, and double plates beneath the tail; but the latter compressed like an 

 oar, which renders them aquatic. 



Finally, we place at the termination of the Vipers certain species which only differ in having single subcaudal 

 plates, either partly or throughout. They are distinguished from the Tisiphones by having no cavities behind 

 the nostrils. 



Some, with entire plates at the base of the tail, compose the Trimerenirus, Lacepede, having large plates on the 

 head, and some of the subcaudal ones double, others single. 



Oplocephaliis, Cuv.— Have great plates on the head, and all the subcaudals single. 



Acanthophh, Daud.; Ophrias, Merrem.— Plates in front of the skull and of the head, the tail terminated by a 

 hook, and all its plates simple, though sometimes there are double ones at its extremity. 



Echis, Merrem. — Small plates on the head, and all the subcaudals single. 



i««(?aArt, Bnigui&res.— Head plated; the muzzle pointed and projecting; anterior half of the tail encircled 

 with entire rings, and the posterior with little imbricated scales both above and below. 



Besides these two tribes of Serpents properly so called, which have been longer known, a third has 

 been discovered more recently, tlie jaws of which are organized and armed nearly as in the non- 

 venomous kinds, but wliich have, nevertheless, the first of their maxillary teeth longer than the rest, 

 and pierced for the purpose of conducting venom, as in the genera with isolated fangs, already described. 



These Serpents form two genera, distinguished from those of the two allied families, by the scaling 

 of the belly and under-part of the tail. 



The Bongars {Pseudoboa, Oppel.) — 

 Possess, hke the Boas, the Rattlesnakes, and the Scytals, simple jilates beneath tlie belly and tail. 

 Their head is short, covered with large plates, and the occiput hut slightly bulged. Their most charac- 

 teristic distinction, however, consists in their very carinated back being furnished with a longitudinal 

 range of scales, broader than the lateral ones, as in the Dipsas. 



They inhabit the East Indies, where they are called Rock fsnakes, one of the species attaining a length of seven 

 or eight feet. 



The Hydras {Ihjdnis, Schneider, in part; llydrojMs and Pelamides, Daud.)— 

 Have the back part of the body and tail very much compressed and raised vertically, which, imparting 

 to them the power of swimming, renders them aquatic animals. They are very common in certain 

 parts of the Indian Seas, [and excessively venomous, feeding on fishes]. Linnaeus ranged those that 

 were known to him among the Orvets, on account of the small scales with which they are wholly 

 covered. Daudin has subdivided them as follows : — 



Ilydrophis.— These have a range of scales a little broader than the rest under the belly, as in the Erpetons and 

 Roles ; the head small, not bulged, obtuse, and covered with large plates. Several species are found in the salt 

 water of Bengal, and others in the Indian ocean. 



Pelamides,— have, also, great plates on the head, but their occiput is bulged on account of the length of the 



