On the Genus Icterus ofM. Brisson. ]95 



into the details of many of the subjects represented in it, with 

 respect to the characters of the bill, legs, wings, &c. ; so much so 

 as to have caused numerous errours on the part of those syste- 

 matick writers who have trusted to the plates only of the birds as 

 guides to their arrangement. I have moreover to add that I have 

 at present before me specimens of some birds, the plumage of 

 M'hich is wholly black, and which evidently belong to the 

 latter groups of the subfamily before us. These for similar con- 

 siderations to those stated above, I equally refrain from referring 

 to their respective stations. Where the colouring only of birds 

 is described, and that colouring as in the present case, is common 

 to many birds, it is impossible to determine with accuracy, or 

 without much labour, what bird is alluded to in such descriptions. 

 The characters of " atra nitens, dor so subviolaceo" or " atro- 

 violacea, alts caudaque viridi-niientibuSy^ will apply with equal 

 precision to twenty birds, differing not merely as species, but by 

 strong generick peculiarities. Fearing therefore I should only 

 add to the number of the synonyms of these birds, or encrease 

 the confusion already existing among them, were I to attempt to 

 describe them myself, or to refer them to descriptions already 

 given, I shall pass them over in the present sketch, which is 

 merely intended to point out the different modifications of form 

 exhibited in the genus Icterus, Briss,, and the typical representa- 

 tives of each. I hope hereafter to complete the group. 



On looking back then to the different groups which have come 

 before us, we may perceive that the present subfamily Icterina 

 embraces five prominent types of form, which, although sufficiently 

 distinct, are yet found to pass into each other, and to exhibit a 

 series of affinities returning into itself. Beginning with the genus 

 Cassicus, we may perceive that it is separated from the remaining 

 groups by the rounded base of the bill as it passes backwards 

 over the front of the head ; and yet that it accords with the suc- 

 ceeding genus QuiscaluSy by the strength of the same bill, by the 

 structure of the wings, and the encreasing graduation of the tail 

 exhibited in some of its extreme species, more particularly in the 

 Cussicus cristatus. The group of Quisculus again shows a devia- 

 tion from the preceding group in the partial curvature of the bill, 



n2 



