116 MR. A. H. GARROD ON THE MUSCLES OF BIRDS. [Feb. 3, 



structural character or a combination of characters to turn up which 

 would give clear indications of the most important divisions of the 

 bird class. My search has, to my own mind, been fairly satisfactory 

 in its results ; for the classification at which I have arrived appears 

 to have a practicability about it which is decidedly promising. 



The oft-named ambiens muscle is, in my idea, the key to the 

 whole. In some families it is present, in others absent. By com- 

 bining all those in which it is found into one subclass, to be subse- 

 quently termed Homalogonatce (typically kneed, because the ambiens 

 runs in the tendon of the knee), and all those in which it is absent into 

 a second, to be subsequently termed Anomalogonatce (abnormally 

 kneed), a primary division is the result which the following facts will in 

 great measure justify. It may be stated at once, however, that there 

 are a few undoubtedly homalogonatous birds in which the ambiens 

 muscle is absent ; there cannot be any anomalogonatous birds in 

 which it is present. 



The following table (Table I.) contains the names of the various 

 most important divisions of the Class of Birds, arranged according 

 as they are homalogonatous or anomalogonatous. Those homalogo- 

 natous divisions with an asterisk (*) against them do not possess the 

 ambiens muscle in any of their genera ; in those with a dagger (t) 

 it is wanting in certain genera only. 



Table I. 

 Class AVE S. 



Subclass HOMALOGONATH. 

 Order I. GALLIFORMES. 



Cohort (a) Struthiones. 

 Family 1. Struthionid^e. 



Subfamily 1. Struthionirue. 

 „ 2. Rheina. 



Family 2. Casuariid,e (*). 

 „ 3. Apterygib-jE. 



,, 4. TlNAMID^E. 



Cohort (/3) Gallinace;e. 

 Family 1. Palamedeid^e. 

 „ 2. Galliisle. 

 „ 3. Rallid^e. 

 „ 4. Otidid^e. 

 Subfamily 1. Otidince. 



„ 2. Pkosnicopterince. 

 Family 5. Musophagid^e. 



„ 6. CUCULID.E. 



Subfamily 1. Centropodince. 

 „ 2. Cuculince. 

 Cohort (y) Psittaci (f). 



Order II. ANSERIFORMES. 

 Cohort (a) An seres. 

 Family 1. Anatid;E. 



