260 ON THE OSTEOLOGY OF PTEROCLES, ETC. [Nov. 25, 
lege of Surgeons, a few months ago: this example is the skull of the 
Trigonal Cayman. 
‘There are three on each side in this latter creature, united by a 
triradiate suture; in the Tinamou, however, there are six or seven 
larger and several smaller ossicles on each side. At first sight it 
seems as though half the sclerotic ring had been attached there by 
accident ; these supraorbitals are, however, much stronger than the 
sclerotals. 
«The sternum of the Tinamou is greatly differentiated when com- 
pared with that of a Rhea or Emeu; but all the improvement is 
gallinaceous. It is absolutely the most unique and wonderful of all 
the sternums I have seen, the variations of which in the bird-class, 
as is well known, are very great and very exquisite. 
‘The presence of a somewhat deep keel, so seemingly fatal to the 
struthious theory of this bird’s relationship, strange to say, turns out 
a good proof of its validity and truth. Every one who has watched 
the larger-winged Ostriches must have noticed their habit of lifting 
their wings—a motion performed by the middle pectoral muscles or 
levatores of the humerus: to these muscles nearly all the keel of the 
Tinamou’s sternum is devoted, a most narrow, small corner being 
left for the thin abortive depressores—muscles which, not only in 
typical birds, but also in the heavy Gallinaceze, are of very large size. 
The small ‘ furculum’ is Pluvialine; but the coracoids and scapulze 
come very near to those of the common Fowl. 
«The blending of the last cervical with three out of four of the 
dorsal vertebree is gallinaceous ; but the absence of costal appendages, 
except a small one on the second true rib and a trace on the third, 
is struthious enough. The pelvis looks, at first sight, but a few re- 
moves from that of the Hen; and in so much as it differs from the 
pelvis of the Emeu or the Apteryx (which have very compressed 
pelves, whilst this is broad and gently arched), in the same degree 
does it approach that of the Fowl. The preacetabular spur of the 
ilium is there; but the postfemoral part of that bone looks as if it 
had been pared away, leaving an enormous ischiadic notch, which is 
a foramen in typical birds. The tail is a mere pretence (as Wagler’s 
term Nothura well expresses); the caudal vertebree are therefore but 
little better than those of an Ostrich. The strong legs leave us the 
choice, at first sight, of referring them to either the Fowl or the 
Ostrich ; and the heel, small and high up, is gallinaceous. But the 
tarso-metatarsus, covered with transverse plates in front, has the 
posterior two-thirds invested by an intensely strong imbrication of 
horny scales; thus adapting the leg of the bird to that odd sitting 
position (about as elegant as that of the Ass in the first stage of the 
erect posture) in which the Struthionide delight.” 
