410 



2269. The last six dorsal and first three lumbar vertebrae. 



They show the progressive metamorphosis of the accessory tubercle into the metapophysis 

 and anapophysis, which coexist with the diapophysis upon the ninth dorsal. The diapophysis 

 subsides into a feeble ridge in the three following vertebra, but reappears and rapidly in- 

 creases in size in the lumbar series. The convergence of the spines towards that of the ninth 

 dorsal is well shown in this series. 



2270. The left humerus. 



It shows the perforation and the characteristic form of the inner condyle. 



2271. The left radius and ulna. 



These are remarkable for the extent to which they are joined together at their distal ex- 

 tremities. 



2272. The bones of the right hinder extremity. 



They show the fabellse and the interarticular cartilages of the knee-joint. 



The following are parts of the same skeleton of the Grey Squirrel (Sciurus cinereus) : 



Hunterian. 



2273. The cranium, vertically bisected. 



There are two perforations in the squamosal above the tympanic. 



2274. The rami of the lower jaw. 



2275. The five anterior cervical vertebrae. 



The vertebral artery has been injected and preserved, to show its course through the trans- 

 verse processes of these vertebrae, and through the neural arch of the atlas. 



2276. The remaining vertebrae of the trunk, the pelvis, and base of the tail. 



The seventh cervical has a small tubercle above the neural arch, not a spine. The spine 

 of the first dorsal is short and inclined forwards ; those of the second and third are of nearly 

 equal length, and the rest gradually become shorter. Eight pairs of ribs directly join the 

 sternum, which consists of seven bones : the manubrium is strongly carinate below. There 

 are 12 dorsal and 7 lumbar vertebrae. The interspace between the ninth and tenth dorsal is 

 that towards which those of the other trunk-vertebrae converge. The metapophyses are first 

 distinct upon the tenth dorsal. The anapophyses disappear in the last lumbar. The first 



