OF THE OIINITHORYNCHUS PABADOXUS. ITS 
tensive sweeping semicircular motion, and thereby 
enables the whole shoulder to alter very much its 
relative situation to the clavicle and sternum. It 
is the episternal of Geoffroy. 
The dorsal portion of the scapula. 
The little process, I have considered in the text 
as the acromion scapulae. Here there is a move- 
able articulation of the clavicle b, and of two 
bones marked h, considered by me as analogous 
to the Jburcliette or merry-tliought in birds. They 
are named Acromial Processes by Geoffroy. 
They are intimately united to the horizontal 
branch of the clavicle, and are articulated to the 
scapula, by means of a joint admitting a certain 
degree of motion. They have been omitted in 
the very spirited drawing of this part of the osse- 
ous system of the Ornithorynchus paradoxus, by 
Mr Clift, and published in the Philosophical 
Transactions for 179^- 
2. Represents an anterior view of these bones ; the 
letters Ji and J' refer, as in the preceding figures, 
to the merry-thought and dorsal portion of the 
scapula ; i marks the articulation between these 
bones at the part I have called aa^omion. 
3. Is taken from a figure in the Philosophical Trans- 
actions for 1818, Part I. Plate II. It is a re- 
presentation of the bones entering into the com- 
position of the shoulder, in a fossil animal de- 
scribed in the same work. 
Two flat bones, peculiar to the sternum of this ani- 
mal and the Ornithorynchus. 
b, A flat bone, behind which is concealed the union 
of the edges of the two flat bones just mentioned, 
(This is considered by Sir E. Home as the ster- 
num of tiie animal; and is called so i\t r.) 
