296. PROF. HUXLEY ON THE alectoromorpiijE. [May 14, 



8. The coracoid has no subclavicular process. 



9. The scapular end of the furcula is not expanded ; but it forms 

 almost the whole, or the greater part, of the inner wall of the canal 

 for the tendon of the middle pectoral muscle. The hypocleidium * 

 is well developed, and presents very various shapes. 



10. The acromial process of the scapula is very short. 



1 1 . The humerus has no supinator spine, and the anterior edge 

 of the deltoid crest is obliquely bevelled off. 



12. The hypotarsus (commonly called the calcaneal process of 

 the tarso-metatarsus) is traversed by a single canal. 



13. The hallux is always present, though it varies greatly in size 

 and position. 



The AlectoromorphcB, distinguished from all other birds by the 

 totahty of these characters, are divisible into two primary groups, 

 which I shall term the Peristeropodes and the Alectoropodes. In 

 the former division the foot is Pigeon-like, the long hallux being on 

 a level with the other toes ; while in the latter it is Fowl-like, the 

 hallux being short and raised. 



The Peristeropodes have the following osteological characters : — 



1. In the sternum the osseous junction of the metosteon with the 

 lophosteon is broad, the inner notch being less than half as long as 

 the sternum itself (fig. 1, p. 297). 



2. The pleurostea end in front in short and obtuse " costal pro- 

 cesses" (c.^j, fig. 1), the anterior edges of which are at right angles, 

 or nearly so, with the axis of the sternum. 



3. The hallux is on a level with the other toes ; and its basal 

 phalanx is about as long as, or may be longer than, that of the 

 third digit. 



These characters are diagnostic of the Peristeropodes. In addi- 

 tion, the second metacarpal presents no backward process near its 

 proximal end ; the phalanx of the third digit of the manus has no 

 basal projection or tubercle ; and, in the pelvis, an ileo-pectineal 

 process is generally absent ; if present, it is weak. In all those 

 species in which I have been able to observe it, the vomer is strong, 

 and compressed from side to side. 



The Cracidce and Mer/apodidee compose this group. It may ex- 

 cite surprise that birds so unlike in habit should be arranged even 

 in the same division ; but I must go further, and declare that after 

 a careful examination of the genera Talegalla, Meyapodius, Crax, 

 (Pauxi,) Penelope, Oreophasis, and Ortalida, I am at a loss to dis- 

 cover any important osteological differences whatever between the 

 Megapodidce and the Cracidce f. The hind toe, however, appears to 

 be longer in proportion to the rest, and all the toes in proportion to 

 the tarso-metatarsus, in the Megapodidce. 



It is a singular circumstance, however, that the form of the pelvis 



* The process developed from the symphysis of the conjoined clavicles. 



t In the degree of pneiiniatiei(y of tlie bones, the Cracidce and the JSIcgapvdida' 

 differ inimciisely, as Mr. Parker has akeady shown ; but this is a character of 

 no systematic value. 



