MORPHOLOGY OF THE GALLINACE.E. 221 



fused together : total 49. The procoelous cup of the atlas is deeply scooped for the 

 odontoid process of the axis ; neither of these vertebra; have riljlets : those on all but 

 the lower cervicals are strong- and sharp-jiointcd. 



Small spines are seen from the axis downwards (or backwards) ; these begin to be larger 

 and square in form near the end of the cervical series, the last of which is fused with 

 the compound dorsal piece ; the 15th has a small styloid rib, the 16th a perfect vertebral 

 rib, but no sternal piece. From the 5th to the 10th inclusive, the carotid canal is pro- 

 tected at its sides, but not below. On the 11th, the lower spine, present in the 2nd, 3rd, 

 and 1th, is renewed, and in the first three of the fused dorsal tract these are united 

 below and form a bifcnestrate keel ; the last fixed and the single free joint have each a 

 small lower sjiine. 



The upper spines of the last cervical and first three dorsals form one continuous oblong 

 plate of bone, which rises from before backwards ; the free spine of the last dorsal is the 

 highest of all, and those of the lumbo-sacral become lower again, and the spine dies 

 out on the last sacral projier. The sacral spines are fused together, and to the pre-ilia, 

 and thus form a pair of galleries which open, behind, over the 1st sacral proper. The 

 last, or free, dorsal lies under and supports the pre-ilia. So arbitrary are the terms that 

 we use in describing these parts. The diapophyses of the last cervical and first three 

 dorsals are ankylosed and form, right and left, a strong fenestrate eave over the thorax ; 

 the tubercles of the ribs articulate under its edge, and the capitula fit into small 

 parapophysial raised cups at the junction of the neural arches with the centra ; these 

 become lower behind, so that those ribs have their forks longer than in front. The 

 sjiinous carinature of the dorsals does not affect the articular facets that form the free 

 joint, they are all cylindroidal or heterocoelous. The " buttresses " are strong, 

 those on the 1st lumbo-sacral are the feeblest ; they are high up and feeble on the true 

 sacrals; the 1st uro-sacral has a strong pair of rilj-bones, the rest only diapophyses 

 which gradually become like those of the free caudals. The interspaces, right and 

 left, are open between the pre-iHa and filled in with periosteal bone between the post- 

 iha. The hind part of the sacrum is not fused to the hip-plate ; the fore part is 

 largely ankylosed, yet the last two buttresses are free. All these things have been 

 weighed and measured in the balance, and by the rules of Teleology ; and the result is a 

 fine combination of strength and elasticity. These firm-footed birds only show their 

 clumsiness in flight. 



The caudal vertebrse are seen at once to belong to a bad flier ; the intercentra that are 

 developed, as a rule, in relation to the depressores coccygis muscles, are absent ; the spinal 

 processes are represented merely by a pair of tubercles ; the uropygial bone is a long 

 triangle ; it is sharp-edged and strong : the articulation of the caudals is gently biconvex, 

 with a fibro-cartilaginous junction, and no synovial cavity, such as is seen in the last two 

 joints in many of the higher kinds of bu'ds. 



VIII. — The Sternum and Shoulder-girdle of the Chick, 1st Stage. 

 For still earlier conditions of the bml's sternum and especially that of the Chick, I 

 must refer to Miss B. Lindsay's valuable paper (P. Z. S. 1885, pp. G81-71G). In my 



SECOND SERIES. — ZOOLOGY, VOL. V. 34 



