190 ON THE PHYSIOGNOMY OF SERPENTS. 



rows of dark oval spots ; a broad black streak behind the 

 eye. Japan. 



13. Trigoxocephalus Cenchris. — From North Ame- 

 rica. Very distinguishable by its small occipital plates 

 (which are sometimes entirely wanting), and by the scales 

 of the occiput, which are roughened into tubercles instead 

 of keels ; form massive. S. 130 + 43. Body ornamented 

 above with large bands of coppery brown, which permit 

 the ground colour to appear as large lozenge-formed spots, 

 of a gre^ash colour. 



ROT ALUS. 



The second genus of the True Venomous Serpents. They 

 are peculiar to the New World, and prefer inhabiting dry 

 uncultivated places ; we may say, that they take the place 

 of the Vipers in botli Americas. They have the nasal 

 fosse like the Trigonocephalus ; but their form is more 

 robust, their head thicker, their tail armed at its extre- 

 mity either with a sounding instrument called a rattle, or 

 with a hard scale prolonged into a long and sharp point. We 

 only know four species of this genus, some of which arrive 

 at a size superior to any other venomous snake. 



1. Crotalus horridus. — The great Crotalus of South 

 America. It has a muzzle covered with 3 or 4 pairs of 

 plates ; 29 rows of lozenge-formed scales, surmounted with 

 a sharp carina. S. 145 + 25. Above of a yellowish brown, 

 variegated on the back by a range of broad lozenge-shaped 

 spots. 



2. Crotalus Durissus. — Replaces the last in North 

 America, and is found in Mexico. Very much allied to 

 the C. horridus ; but it has only 2 pairs of plates on its 

 muzzle ; the carma on the scales is less developed, the eyes 

 are smaller, the colours darker, the spots often form bands, 

 and the tail is black. S. 170 + 22. 



3. Crotalus miliarius. — A small species of North 

 America. Very recognisable by its head, covered on the 

 top with 9 well developed plates ; 23 rows of scales. S. 

 131 + 26. Eye large; colour a reddish gi'ey, varied by 

 three series of darker spots. 



