396 MR. E. DEGEN ON ECD^SIS. 



Ill this chart arc entered all the tracts and the various longitudinal rows of f'eatliers 

 of which they consist. The rows against which an asterisk has been placed are those 

 which form centres from which the moult proceeds. The pointed ends of the blackened 

 bars denote approximately the beginning of moult of that particular row of feathers. 

 The time of the completion of the moult for the same is indicated at the point where 

 tlie shading reaches its maximum by filling ui) the space between the parallel lines 

 which divide it from the neighbouring bar. 



Beginning and completion of the moult of each row is measured by the common 

 standard, namely, that of the development of the Metacarpo-digital Memiges, whose 

 numbers in this order from right to left are placed at the head of the Table, as are also 

 those of the Cuhitals and the Fennx iwllicis for chronological comparison. A similar 

 arrangement has been provided in this table for the rectrices and their coverts at the 

 bottom. 



The Spinal or Dorsal Tract (Pteryla spinalis). 



This is of a well-defined Passerine form, and partakes of the type under which 

 " Nitzsch" (37, pp. 79 & 80) subordinates Cuvier's Group of the Dentirostres as follows : — 



"A. With 12 rectrices. 



" a. Saddle without a space. 



" 1. Barita. — . . . . saddle short, broadly rhombic, acute angled. Ij. strepera, 

 JB. destructor, B. varia." 



But it also partakes in part of the description which follows for the character's 

 applying to his second division of this group, between which it seems to fit in, namely : 

 " 2. Thamnojihilus, seu Vanga, and Lanius, species undulatus and procerus" in which 

 he refers to " twenty remiges which are all very broad and obtuse, graduated as far as 

 the fifth [our VI.], which is of the same length as the sixth [V.] and seventh [IV.]." .... 

 And further : " . . . . the saddle is heart-shaped reversed, emitting a single row of 

 feathers from its middle as the commencement of the rump-band." 



From this definition of the rump-band Gymnorhina tihicen deviates by emitting not 

 only this single row, but two additional ones as well, whose feathers alternate by means 

 of quinqunx from 3 to 2 for about 7 or 8 of these sets, from whence a short distance 

 backward to the oil-gland the tract broadens further out into two more additional rows, 

 making 5 in all. 



The saddle portion itself in its widest diameter, which is placed two-thirds back- 

 ward, consists of 12 rows, tapering out to 6 rows on its anterior or interscapulary 

 portion, which further in front widens out into from 2 to 3 additional lateral rows, 

 from which latter region it broadens out into the head tract. 



I have found the moult to proceed from three distinct main centres on. the principal 



