302 PROCEEDINGS OF THE CANADIAN INSTITUTE. 



and epiotic, and almost occludes the opening of the temporal fossa, 

 while the extremity of the vertical limb articulates with the side of 

 the basioccipital, and a process on its ventral surface near its junc- 

 tion with the transverse limb articulates with the stout transverse 

 process of the fourth vertebra. The upper portion of the lower 

 division of the secondary girdle lies in the deep groove between this 

 process and the extremity of the lower portion of the transverse 

 limb. 



The lower piece consists of two portions coalesced, which may be 

 denominated the mesoclavirula (Fig. 6 MCI) and infraclavicula (1 01), 

 no trace of the constituent parts, however, persisting. Above are 

 three processes. The anterior (ap) which projects directly upwards, 

 fits into the deep groove mentioned above ; the median (mp) pro- 

 jecting backwards and upwards, lies behind the lower portion of the 

 ti'ansverse limb of the supraclavicula, and prevents excessive down- 

 ward and backward motion of the arch ; and the inferior (ip), which 

 projects directly backwards, lies quite free immediately below the 

 the skin, its outer surface being roughened by minute tooth-like 

 tubercles. The axis of this portion is almost directly vertical, below, 

 however, the bone curves inwards, becomes horizontal, and is united 

 by ligament with its fellow of the opposite side. The upper surface 

 of this portion, which is thin, is smooth. The under surface presents 

 several points for examination. Just below the base of the inferior 

 process mentioned above is a deep semi-circular groove (sg), in which 

 the correspondingly shaped basal process of the first fin-ray runs. 

 The ridge which bounds this on the outside is continued downwards 

 and then inwardly on the under surface, and with a corresponding 

 though slighter parallel ridge forms a groove. With the posterior 

 ridge the anterior edge of the coracoid (cor) articulates — a broad 

 process (br) extending across to the anterior ridge near its outer 

 extremity, and thus forming in this region a canal. By the expanded 

 outer and posterior portion of the coracoid overlapping the under sur- 

 face of the coalesced meso- and infraclavicula in that region, and not 

 further inwards, another canal is formed, which unites with the one 

 already described, both containing parts of the same muscle. No 

 post-clavicula is present. 



The two pieces, coracoid (cor) and scapula (sc), of which the 

 primary girdle is originally formed have also become quite coalesced. 



