322 Proceedings of the Royal Physical Society. 



Humming Birds and the Swifts together in one suborder. 

 The CYPSELIFOEMES, then, present a different style of wing 

 coverts from the parallel groups amongst the PASSERES — 

 the Sunbirds and the Swallows (see Fig. 2a). The difference 

 in style can hardly be attributed in these cases to difference in 

 mode of life. Eather does it appear to me to represent an 

 archaic feature, dating back to the remote past, when these 

 now-useless morphological characters served some real purpose 

 in the economy of the possessors. 



Two other groups of birds possess much the same simple 

 style of wing coverts as the CYPSELIFOEMES. These are 

 (1) the Birds of Paradise (Fig. 3), and (2) the Trogons. In 

 the Paradisid^ every individual I have examined showed 

 the whole of the feathers above the Major Coverts lying with 

 distal overlap, and with, generally, much the same arrange- 

 ment as in the CYPSELIFOEMES. The number of rows, 

 however, is considerably increased in the group under notice. 



11. The Passerine Style. — The next advance in com- 

 plexity is represented by the great group of the PASSEEES 

 proper. These generally possess, in addition to the Marginals 

 seen in the CYPSELIFOEMES, one row of Minor Coverts, 

 with distal overlap, see figure of Skylark (Fig. 4), and one 

 row of Medians, whose overlap is generally proximal through- 

 out nearly the whole of this large group. The Corvid^ 

 (see Fig. 5) differ slightly from the normal type, inasmuch 

 as a few of their anterior Medians overlap distally. In 

 this respect they make an approach, superficially, to the 

 Paradisid^, as they are commonly believed to do in some 

 other respects. 



It may be said, therefore, in general terms, that almost 

 the whole of the birds with an segithognathous palate, with 

 coeca, with a nude oil-gland, with the fifth cubital remex 

 present, devoid of the amhiens muscle, and whose young are 

 hatched helpless and naked, have simply the ordinary rows 

 of Marginals, one row of Minor Coverts, whose edges 

 invariably overlap distally (which are not present in every 

 group), and with one row of Medians, whose overlap is 

 proximal in every case. 



Some exceptions to the general rule have already been 



