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 (IC), 
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 
transverse limb of the supraclavicula, and prevents excessive down- 
ward and backward motion of the arch ; and the inferior (7p), 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 isa 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. 
