288 NORTHERN ZOOLOGY. 



CORVIDiE.— CROWS. 



There are some singular and highly interesting peculiarities, exclusively belong- 

 ing to groups pre-eminently typical, which demand the deepest attention of the 

 philosophic naturalist. One of the most striking of these is the great difference 

 between those forms which belong to perfect and natural genera, strictly so 

 termed*. We might cite the restricted genera Tanagra, Cashmorkynchus, and 

 Coccothraustes as remarkable examples of this fact, and as groups which would well 

 repay the most minute analysis. This peculiarity sometimes extends to higher 

 groups ; and in the present family, the most pre-eminently typical in the whole 

 circle of Ornithology, it is more striking than in any other. It is, perhaps, to this 

 circumstance that we must attribute the very imperfect manner in which the internal 

 relations of the Corvidce have been illustrated, and the artificial distribution that 

 has been made of the groups it contains. Our space^ indeed^ will not permit us 

 at present to throw much light upon the subject, further than what may be gained 

 by studying the following table of the sub-families : — 



Analogies. 12 Typical group. Sub-families. 



Conirostres. Wings lengthened, obliquely pointed; lateral toes equal. Corvince. 



2. Sub-typical group, 

 Dentirostres. Wings shorter, rounded, convex ; lateral toes unequal. Garrulities. 



3. Aberrant group. 



Scansores. ( Bill short, entire, light; feet short \ Crypsirince. 



Tenuirostres. I ****** K ? 



Fissirostres. ( Bill slender, lengthened ; feet short ...... j Fregilince. 



A glance at the modern arrangements will show how essentially we differ from 

 all ornithologists who, like us, have attempted to elucidate this very intricate 

 family. The tests, however, by which every series of animals thought to be 



* A genus, in whatever higher group it may occur, can never, strictly speaking, be pronounced perfect or natural, 

 until it has been so demonstrated : or, in other words, until its five sub-genera, representing all the higher groups, 

 have been detected. If any one of these types be missing, the genus is imperfect ; and although it may still contain a 

 sufficient number to justify us in the belief that it is a natural genus, still this fact can only be demonstrated when the 

 circle is completed by the discovery of the missing types. Thus, for instance, the Picidw is an imperfect group : since 

 every representation of the rasorial sub-family is lost, or at least unknown. But the sub-family of Piciance, or true 

 Woodpeckers, when viewed by itself, is perfect; since it contains its five leading types, symbolical of all the higher 

 groups, and these, collectively, describe a circle. The group is thus capable of being demonstrated both perfect and 

 natural. — Sw. 



