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 sis 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 vponderful 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 d&pressores — muscles which, not only in 

 typical birds, but also in the heavy Gallinacese, are of very large size. 

 The small ' furculum ' is Pluvialine ; but the coracoids and scapulae 

 come very near to those of the common Fowl. 



" The blending of the last cervical with three out of four of the 

 dorsal vertebrse 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 vertebrse 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 Strut hionidcs delight." 



