'224 MR. W. K. PARKER ON THE OSTEOLOGY 



a small, distinct rib-head ; in front of that, the small pleurapophyses are all welded to 

 their vertebrae (c.) ; none of them are very long, the longest being at the middle of the 

 neck. The "procoehan" facet of the atlas is only a half-moon, whilst in the Rhea 

 small styles nearly enclose the odontoid process. The cervical vertebrae, generally, are 

 merely like an enfeeblement of the neck-bones of the Great Ostriches. The carotid 

 canals are as imperfect as in Fowls, Pigeons, and their congeners ; and the relative 

 length and thickness of each bone is much like what is seen in ordinary members of 

 those types, and also in the Ostriches themselves. The fusion of the last cervical with 

 those of the dorsals (c.d.) shows the introduction of some leaven or other ; this is cer- 

 tainly not a struthious character : and yet we, regal vertebrates, cannot tell whence that 

 zymotic influence comes, nor whither it goes. The ribs are scarcely longer than the 

 haemapophyses ; they are moderately spongy : the second dorsal has a small appendage, 

 and the next a trace, whereas in the Rhea the first four dorsal ribs have large appen- 

 dages ; the corresponding four ribs in the Apteryx have them very large. The Tinamou 

 comes nearest the Emu in this respect, whilst the Ostrich is intermediate between the 

 Rhea and the Emu. 1 only find eighteen sacral vertebrae (PI. XXXIX. fig. 3, sm., & 

 PL XLI. sm.), whereas the Emu has twenty-two, as may be seen in the young bird'. 

 In the Rhea the middle of the sacrum is abortively developed, and only the embryo 

 would give us the number. The Tinamou's sacral vertebrae are not so stout as those 

 of the Fowl, but they are much like them, the width of the pelvis allowing a much freer 

 development of the transverse processes and stunted ribs than in any of the large 

 Ostriches. Indeed the sacrum, together with the hinder part of the ilium on each side 

 (PI. XLI. fig. 3, il. sm.), gives us a gently convex, smooth surface, more Pigeon-like than 

 even in the Curassow itself, and the spaces between the sacral diapophyses are merely 

 indicated on the upper surface by two symmetrical rows of small foramina. Between 

 the anterior parts of the ilia, however, the spaces are larger, and there is something of 

 the feebleness of the pelvis of the Syrrhaptes (PI. XLI. fig. 5) in that part. The caudal 

 vertebrae have been shorn of their strength ; the spinous and transverse processes are 

 very short and feeble, and there is the slightest attempt at inferior processes (Pis. XXXIX. 

 & XLI. cd.). They are six in number, and the last is evidently three in one ; only four 

 mere centra project beyond the ischium in the Rhea, but I find nine in the chick of the 

 Emu ; indeed the number is very variable in the " Struthionidae." The two or three 

 fused and compressed bones at the end of the Tinamou's coccyx must be contrasted 

 with the ten fused coccygeal bones of the Common Duck. The ralline compression of 

 the pelvis, caused by an almost vertical position of the ossa innominata, has been lost in 

 this aberrant little Ostrich. 



The shape of the iliac bone (il.) is very much like that of the Tree-Partridge and the 

 Curassow, not only in the anterior, but also in the posterior moieties ; it is nearest 



' The extraordinary ornithic fore-and-aft growth of the pelvis is the cause why so many vertebrae should be 

 thus married together, bones which are quite /ree in the Reptilia. 



