604 REPTILES. 



rid^e of the back provided with larger scales than those on the rest of the 

 animal. 



Genus 13.— COLUBER.— Cacier. 



Generic Character. — Abdomen with transverse plates, subdivided under 

 the tail, or forming a double row ; head depressed, with nine larger plates ; 

 teeth nearly equal ; destitute of poison fangs. 



Genus 11— ACROCHOKDUS.— 7/orjw<erf. 



Generic Character. — Body much thicker than tlie tail, both are covered 

 with small uniform tuberculous scales ; jaws provided with two rows of 

 teeth. 



Genus 15.— PSEUDOBOA.— Oppe?. 



Generic Character. — Head short, covered with large plates ; occiput some, 

 what prominent ; plates of the abdomen single, back cariuated with a longi- 

 tudinal row of broad scales. 



Genus ie.—rniUER'ESUB.VS.—Lacepede. 



Generic Character. — Head with large plates ; those under the tail and 

 near the vent single, but double towards the extremity. 



Genus Il.—HYDKOPHIS.—Cuvier. 



Generic Character. — Head small, covered with large plates ; abdomen pro- 

 vided with a row of scales larger than tlie others ; tail compressed. 



Genus 13.— PELAMIS.— Ctwjer. 



Generic Character. — Abdomen and head with larger plates than the body ; 

 occiput tumid ; scales of the body small and equal ; tail compressed. 



Genus 19.— CHERSYDRUS.— C;m'!(?»-, 



Generic Character. — Head small, obtuse ; back triangular and carinatod ; 

 body thicker in the centre, and tapering abruptly towards the tail ; head and 

 body covered with small scales ; abdomen carinated. , j- 



Genus 20.— CROTALUS— Lznn^EMJ. 



Generic Character. — Head broad, triangular, and depressed ; scales cari 

 nated ; tongue bifurcate; a depression behind the nostrils; upper maxil- 

 lary bones with isolated fangs ; tail with transverse platvs ; extremity pro- 

 vided with a rattle of hollow, rigid, articulated, and moveable, plates. 



* Scales of the head and back the same. 



Crotalus horridus.—the Rattlesnake. Plate Ixiv. fig. 7. Described, vol. 

 iv. p. 175. 



Genus 21 —SCYTA'LVS.—LatreiHe. 



Generic Character. — Upper jaw provided with poisonous fangs; body and 

 tail with a row of transverse plates. 



Geniw 22.— ACANTHOPHIS.— Dm«?/?i. 



Generic Character,— Anterior part of the head with large plates ; upper 



