The Swifts 



characters are of rather a technical aspect and need some ex- 

 planation. Enlarged figures of heads among the illustrations 

 should be thoroughly consulted. They show portions embracing 

 the combinations of scales that are of the greatest importance 

 the supraocular scales so called because of their covering the 

 area directly above the eye. From the illustrations it will be 

 noted that the supraocular plates or scales are arranged in a 

 in a large, central series, which are bordered on either side 

 by a row of minute scales. The inner row of these 

 small marginal scales, arranged in crescentic form are, among 

 all the species, in a single row. The outer marginal scales, how- 

 ever, may be present in one, two or three rows, according to the 

 species. Hence we have an important distinction upon which 

 to base a key. The genus has been treated with more detail 

 than Ufa, and a concise, descriptive list of the species follows 

 the key. All complicated phraseology has been carefully omitted 

 from the former, for the writer believes that the beginner should 

 consider a difficult genus like this from a bird's-eye point of view 

 for the most satisfactory results, rather than plunge into a be- 

 wildering mixture of comparisons. 

 The key follows: 



Division A. A row of large supraocular plates, with a 

 single internal border and one external row 

 of small scales. 



Sub-division I. Internal border of small scales extending 

 around forward two-thirds only, of cres- 

 centic margin. 



Color phases. Grayish or brownish, with transverse, 

 dark wavy bands. No complete black 

 collar. Greenish-gray or scales with green 

 centre; traces of black collar on sides of 

 neck. Size large. 



CLARK'S SWIFT, 5. clarkii. 



Yellowish, with a wide, reddish band on 

 each side; indistinct, brown cross-bars. Size 

 large. BANDED SWIFT, S. fosteromus. 



Brown to blackish; scales spotted with blue 

 or green, and red. One of the largest species. 

 ORCUTT'S SWIFT, 5. orcuttii. 

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