CRACIDS. | OSTEOLOGIA AVIUM. | OPISTHOCOMIN®. 
triangular at its upper extremity, with a channel down the front, flattened towards its 
lower extremity ; os calcis projecting considerably, with a very slight ridge provseding 
downwards from it. A supplemental metatarsal bone projecting much backwards, 
not twisted on its axis, tapering and flattened upwards; tubercles for the articulation 
of the feet broad; toes long. 
This curious bird appears to be nearly allied to the guans, but differs from in 
the form of the palatine bones, the hinder margin of the sternum, and furculum. 
There is no Gallinaceous bird that I am acquainted with that has the hinder margin 
of the sternum of a similar form, the nearest approach that I am aware of to the form 
of the furculum is among the cracide in C. Globocera, the process at the junction of the 
rami is very much elongated, but is not nearly sv much so as in the opisthocomus. 
The rami also are curved, while in the latter bird they are straight, and the furculum, 
instead of being anchylosed, or united by a ligament to the point of the keel of the 
sternum, is anychylosed to its medial portion. 
Measurements. 
Tenths, Tenths 
Heneti of humerus Sy. Le Breadth of anterior 4 
Premetasounmlira 8 2a cath ERD margin of ditto iia 7): rare eRe 
Length of metacarpus . . . . 12 Depth of keel EE a oom la 
Menetaiontemurn ye xe oh, LO ~ ene theehhieadd:| 7 oS ae arueee 
Memethvorsmoiay act) yey vee aS Breadth of head 9} 
Length of metatarsus.. . . . Ii Length of pelvis KG: 
Wensia-orsvermam™ ©.) W. a9 6 ipreadth-of pelvis’) ae eae ee 
Breadth of posterior margin . . 1d$ 
Illustration. 
Sop. 2, pl. 2, B. Details, pl. 2. 
