Shuki'.i.dt : ()siko[.()(;y of iiik IIkrodionks. 21i) 



of these are freely movable upon each other. There are no free ribs 

 on the first 15 cervicals, but the pleurapophyses become free upon the 

 sixteenth vertebra, though they are hardly entitled to the name of ribs. 



There is a long, free pair on the seventeenth, but they lack epi- 

 pleural appendages. The pair on the eighteenth vertebra, or the first 

 true dorsal one, connect with the sternum by short haemapophyses. 

 This, and the three following pairs of vertebral ribs have epipleural 

 processes, which are of no great length and are firmly anchylosed to 

 the borders near their middles. The vertebral ribs are inclined to be 

 flat and broad, the ultimate pair being considerably curved both an- 

 tero-posteriorly, and, above, transversely. The costal ribs become 

 gradually longer and longer as we pass backwards, and flatter from 

 side to side. There is a pair of pelvic ribs anchylosed with that bone 

 above, but freely articulating with the longest and last pair of the 

 haemapophyses below. No epipleural spines occur upon their borders. 



This arrangement gives yfzr pairs of costal ribs, in addition to which 

 we find a small pair of "floating ribs." These are attached in the 

 usual way by ligament to the posterior margins of the last vertebro- 

 costal pleurapophysis, lapping over the articulation. 



Taking the leading vertebrae of the chain to include the 17th, we 

 are to observe that they are inclined to be massive, and closely locked 

 together when articulated. None of their processes or spines are 

 prominent. A low, thickened neural spine occurs on the axis ver- 

 tebra, but gradually disappears on the succeeding ones, to become 

 quite absent on the seventh, and does not again develop until we come 

 to the thirteenth. Here it is double, the two halves inclined to come to 

 a point in front. This is accomplished in the fifteenth cervical, where 

 this neural process is distinctly arrow-shaped, with its apex directed 

 anteriorly. Such also is its shape in the sixteenth, while in the seven- 

 teenth this is changed abruptly for the flattened (luadrate process seen 

 throughout the dorsal series of vertebrae. 



The infero-median arterial canal is commenced on the sixth cervical, 

 where it is open. On the seventh to the eleventh it is nearly or (juite 

 closed, to be open again on the twelfth to the fourteenth inclusive, 

 after which it is barely evident. The lateral vertebral canals are 

 slightly indicated even in the atlas, while they are complete and 

 closed in the second to the sixteenth inclusive. We also find parial 

 pleurapophysial spines beginning to develop on the axis vertebra ; 

 on the third they are well-marked and thickened, but becoming long 



