360 



LOWER VERTEBRATES. 



possibly be regarded as a northern variety of the inoie tro]iical Jioa constrictor, 

 though the scales of the head are rather large. The general color is brownish, with a 

 dorsal series of quadrangular brown spots, which is separated from llie smaller spots 

 of the flanks by a pair of light lateral lines. £. constrictor, though properly an inhal)i- 

 tant of Brazil, is rejn-esented in Central America by a variety, isthmica. Along the 

 back is a series of transverse brown bands, each connected with the marks of the 

 flanks by a latero-posterior isthmus, and along each side of the belly is a series of more 



Fig. 21:2. — Boa constrictor. 



or less broken, irregular spots of a black color. £. mexicana is allied to B. imiierator. 

 B. constrictor, proper, inhabits the more tropical portions of South America, though 

 travelers from all parts of the world have almost invariably described large serpents 

 which have come under their notice as ' Boa-eonstrietors,' rendering it extremely 

 diflicult to determine acurately what species they are describing, and bringing the 

 name to so general a use that it has almost lost the primary significance given it by 

 its origin-il propounder, Linne. 



