INNOCUOUS SERPENTS. 173 



the orbit is formed, as in other Ophidians, above by the 

 middle frontals ; and the under part of the tail is furnished 

 with simple plates. The genus is more especially proper 

 to tropical America. Those of the ancient world, are of 

 small size, and of dissimilar forms. 



1. Boa Constrictor. — A terrestrial species of a size 

 between 9 and 12 feet. Very distinguishable by the small 

 smooth scales, which cover the body and the whole head, 

 and are arranged in 67 rows, by its reddish tint relieved 

 by a design composed of broad oval spots, of interlacing 

 bands, and rays of a reddish brown. Form very powerful ; 

 tail short ; head heart-shaped. S. 243 + 58. Inhabits 

 the forests of intertropical America, where it suspends 

 itself to the branches of trees, to possess itself of the small 

 mammifera on which it feeds. 



2. Boa Murina. — The largest of known serpents. 

 Nostrils vertical, approximated to the end of the muzzle ; 

 that part and the lips covered with plates. Eyes directed up- 

 wards ; 47 rows of smooth scales ; head elongated, muzzle 

 rounded, and much inclined at the sides. S. 250 + 66. 

 Fuliginous brown, with two rows of orbicular spots on the 

 back, and a double series of ocellated spots on the flanks. 

 An aquatic and viviparous species, which attains a length 

 of even 20 feet. Same country as the last. 



3. Boa Cenchria. — Of less size than the two last. A 

 teiTcstrial species, vrith the habits of the Boa Constrictor. 

 Head almost as in the two last, but the labial plates are 

 hollowed into a gutter, and the vertical plates are replaced 

 by small scales of an irregular form ; tail short ; nostrils 

 open and lateral ; 35 rows of smooth scales. S. 240 -f- 

 48. Of a yello^vish red-bro^vn ; above ornamented with 

 a double suite of orbicular spots, bright, and bordered with 

 black ; three rows of spots, less broad, and dark coloured, 

 on the sides. The spots are often confluent, forming a 

 reticular design. Country the same as the preceding 

 species. 



4. Boa Canina. — ^Well characterized by its green tints, 

 relieved by white lozenge- formed, dorsal spots ; below 

 yellowish. Anterior teeth very long ; body strongly com- 

 pressed, and particularly adapted for being rolled inwards ; 



