The Swifts 



as regards identification of species, among the North American 

 lizards. 



Distribution. About thirty-five species of Sceloporus are 

 recognised and of these about one-half the number inhabit Mex- 

 ico and Central America, which countries might be termed the 

 headquarters of the Spiny Swifts; they have extended their 

 range into the southwestern portions of the United States, while 

 a few species have reached such northern limits as Oregon and 

 others have extended southward into the peninsula of Lower 

 California. The range eastward has not been pronounced, for 

 with the exception of two species the Swifts do not extend be- 

 yond Texas. Of these, one (5. spinosus) extends eastward 

 from Mexico and Texas along the southern borders of the Gulf 

 States to about Pensacola, Florida. The other (5. undulatus) 

 abounds throughout the Eastern States, from southern New 

 Jersey to Florida, where it may be seen in the country, scamper- 

 ing over every fence and stone wall or upon the trunks of fallen 

 trees particularly in the pinelands. It is the most widely dis- 

 tributed of any of the Spiny Swifts, being found from the 

 Atlantic to the Pacific coasts. 



General characters. As members of their genus, the Spiny 

 Swifts are readily recognised. They are covered above with 

 large, lustreless and coarsely keeled scales, terminating in sharp, 

 spine-like points particularly on the limbs and tail. So sharply 

 pointed are the scales of some of the species, that the reptiles 

 appear to bristle all over, with needle-like spines. The abdomi- 

 nal scales are smooth and polished. The prevailing colours of 

 all the species, above, are gray, brownish, or olive, with darker 

 and wavy cross-bands. The throat and abdomen of male spec- 

 imens display large patches of rich blue, which colour varies 

 in hue according to atmospheric conditions and the activity 

 of the individual. Female specimens exhibit little or none of 

 the blue. 



A few words regarding more precise anatomical characters 

 are necessary before presenting a key to the identification of 

 the species. The characters of the pattern are too weak and 

 monotonous to be alone employed; they are secondarily impor- 

 tant in the sub-divisions of a key. It is from the scalation of 

 the head that we must draw the characters for the formation cf 

 an analytical table of the species. (See figures.) These 



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