XXVUl 



It is not likely, in the case of Passerine birds (which we 

 must consider tlie most highly developed and best adapted for 

 flight) J that they should be quintocubital in the sense of birds 

 of an arrested development. The greatly reduced niimber of 

 cubital flight-feathers, eleven at the most, shows distinctly 

 that their suppression has been carried out more completely, 

 and what appears to be a fifth cubital may in reality be the 

 sixth, which has gone further in the process of disappearing 

 by suppressing the respective coverts as well. In addition to 

 the detailed description of the pterylomorphism in the bird^s 

 wing, and its reflections on the derivation of the various 

 groups of flight-feathers, together with their main coverts, a 

 glance at the latter shows us that we have to deal with two 

 distinct sections of remiges on the ulna. The first section, 

 consisting of two parts, derived from the ord metacarpo- 

 digit, comprises the cubitals 1-5, as well as 6-8, the latter 

 being derived from the lost 4ith digit. The remiges of the 

 foregoing section,^ therefore, cannot be true cubitals, and 

 must consequently be termed "remiges cubitaks spuriie,' 

 or protometacarpo-digitals. 



The remainder of the cubitals, comprising the remiges 9 — x, 

 form the second section and are the true remiges, or '"'remiges 

 cubitales verje.'^ They are always set more closely to each 

 other on the ulna and quite cramped on the olecranon. 

 Together vrnh. the numerous modifications of ectodermal 

 products, it is more than probable that in the course of time 

 the skeletiferous parts and dermal structures have been 

 equally modified, and thus the ulna has been elongated, in 

 order not only to receive the flight-feathers of the dispens- 

 able 3rd and -ith metacarpo-digits, but also to supply the 

 requirements of greater power of flight, an economy abso- 

 lutely indispensable to the class Aves. 



Having read and studied the various works and papers 

 treating on the subject of tlie morphology and pteryolo- 

 grapliy of the bird^s wing, I have failed to find any reference 

 us to the exact value of the quills of the 1st digit, or penn?e 

 poUicis. 



Mr. Wrav and others seem to content themselves with 



