30 Mr. W. A. Forbes on the late Professor Garrod's 



followed by those of the seven groups above mentioned as the 

 exceptions to the combination of cseca and a tufted oil-gland 

 amongst the Homalogonatee. 



Thus, of the whole series of Homalogonatous birds, not 

 one, except certain Parrots (the most specialized, no doubt^ 

 of all that series), has any combination of these characters 

 that could lead to its inclusion with the three combinations 

 present in the Anomalogonatse. 



The grand division into Homalo- and Anomalogonatse was 

 primarily made by Mr. Garrod on the strength of the facts 

 here tabulated. But subsequent investigations of quite dif- 

 ferent points have much strengthened his original position. 

 One of these is the difference in distribution of the plantar 

 tendons in the two groups of zygodactyle birds, already de- 

 scribed above. I believe the removal of the Cuculidse and 

 Musophagidse from the so-called '^'^ Picarian ^^ birds, or " Coc- 

 cygomorphae," on account of their possessing the ambiens 

 muscle, absent in the others, was considered by many natu- 

 ralists a striking proof of the artificial nature of Prof. Gar- 

 rod^s system. But it has been most remarkably confirmed 

 by his later discovery, and so is, to my mind, one of the most 

 convincing proofs of the correctness of his arguments, until, 

 at least, some other explanation shall be given of the facts here 

 adduced. Yet another confirmation is afforded by the ptery- 

 losis. I here reproduce Prof. Garrod^s own words : — " My 

 study of pterylography has led me to look upon the nature of 

 the dorsal tract as all important in determining to which great 

 group of birds, the Homalogonatse or Anomalogonatee, any 

 doubtful family belongs. When the dorsal tract develops a 

 fork between the shoulders, a bird is Homalogonatous ; when 

 the tract runs on unenlarged to near the lower ends of the 

 scapulae, then it is Anomalogonatous " (P. Z. S. 1878, p. 931). 



Very few exceptions to this rule obtain — the Coraciidse, in 

 that they develop an interscapular fork, although in other 

 respects truly Anomalogonatous, being, perhaps, the most 

 marked one. 



The Homalogonatous nature of the Cuculidse is fully born 

 out by their pterylosis, the dorsal tract in them dividing 



