80 Transactions.— Zoology. 
SrERNUM. Pl XIL, fig. 1, and XIIL., figs. 1, 2. 
This bone is almost perfect, baving lost only a few lines of its inferior 
margin, and, though it differs considerably from the characters attributed to it 
by Professor Owen, this is, without doubt, due to his not having had a 
connected fragment of the superior portion of the bone, so that its enormous 
posterior concavity was not appreciated. It is chiefly remarkable for its 
regular oblong shape, without any irregularities of outline or unossified inter- 
spaces. The texture must be cancellated, for, though apparently thick and 
massive, it is very light in proportion to its size, as will be seen in the 
appended table. Tts general form is scaphoid, the concavity being very marked 
in the upper half, amounting to one inch in depth measured from a transverse 
chord, and to one-and-a-half inches in depth if measured from a longitudinal 
chord; the total length of the latter being 7 inches. The anterior width at 
the costal processes (a) is 4 inches, and at the posterior end of the costal 
border 3 inches 6 lines, 
The costal border (¢-e’) occupies half the lateral margin of the bone, the 
posterior half of the line being only slightly concave interiorly, and exteriorly 
being flat in the middle and sloping very slightly to the inferior angles. The 
superior margin is thin, and presents a wide mesial notch (f) and two lateral 
notches (y), which are bounded exteriorly by the costal processes, which project 
backwards and upwards for 6 lines. The coracoid grooves (b) are 1 inch 
6 lines in length and 2 lines in depth of anterior border. They are separated by 
a slight triangular interspace f/f’ ) 5 lines wide, beneath which is a smaller 
triangular pit (4). The keel (c) commences by two angular ridges bounding 
this pit posteriorly, and forms a blunt process 3 inches in length (c-c’), 
expanded anteriorly to a rough tuberculate surface 4 lines in width and 9 in 
length, and then compressed into a narrow tuberculate ridge that is gradually 
lost in the smooth convex surface of the bone at less than one-half the distance 
from its superior margin. The greatest elevation of the keel above the convex 
surface of the bone is less than 3 lines. The impression (d) for the attachment 
of the pectoral muscle extends from the exterior angle of the coracoid notch 
towards the posterior part of the keel, including a triangular area' which 
occupies only one-sixth of the exterior surface of the bone, showing the 
extremely limited and feeble attachment of the great muscles of flight. Large 
pneumatic foramina (i) exist in the interior of the bone at the upper 
angles, and one (7) on the exterior surface on the left side only. 
Furcutum. Pl XII, figs. 2 and 3. 
The clavicles are completely joined into a smooth, slightly-compressed 
furculum, like that of the goose, except that the antero-posterior curvature is 
confined to the articular processes, which diverge 1 inch above the general 
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