The Swifts 



Large supraocular plates numerous six; 

 marginal scales numerous and minute; dark 

 green, with a pale, greenish band on each side 

 these separated by about fourteen rows of 

 scales; two series of obscure blotches; size 

 large. VARIABLE SWIFT, S. variabilis. 



Gray, with wavy, darker cross-bands. An 

 indistinct stripe on each side these separated 

 by about ten rows of scales. Size small. Head 

 plates not always corrugated. Occurs from 

 Atlantic to Pacific Coasts. 



COMMON SWIFT, S. uiidulatus. 



Scales more bristling than preceding; blotches 

 rather triangular. Occurs on the Pacific coast 

 only; size small. 



PACIFIC SWIFT, S. undulaius, var. occidentalis. 



Pale bands separated by six or eight rows of 

 scales; otherwise very similar to 5. undulaius. 

 Size small. Restricted to Texas. 



THAYER'S SWIFT, 5. tbayeri. 



Olive-gray; a very narrow, but bright yel- 

 low line on each side these lines about twelve 

 scale rows apart. Two series of dark crescents 

 on back; size small. 



STRIPED SWIFT, S. scalaris. 



Division D. A double series of moderate-sized, supraocular 

 plates, bordered internally with a row of smaller 

 scales and externally by one or two rows of 

 small scales which latter rows may be of ir- 

 regular formation. 



Sub-division I. A broad, jet-black collar, completed above. 



Scales very large and bristling. Obscure, 

 dark cross-bands on olive ground; a broad, 

 black collar, margined with yellow and com- 

 pleted above. Size very large. 



COLLARED SWIFT, S.torquatus, var. poinsettii. 



Sub-division II. No collar; pale bands on sides. 



Olive gray. A pale band on each side, about 

 two scales wide and separated by about eight 

 scale rows. Obscure cross-bands. Size moder- 

 ate. SAGE-BRUSH SWIFT, S. graciosus. 



Following is a descriptive list of the species: 

 The first group of the Spiny Swifts to be considered, is 

 Division A of the key, with which the inner border or margin 

 of small scales along the edges of the supraocular plates is in- 



130 



