974 MR. R. LYDEKKER ON REMAINS [Nov. 19 
to a process on the preaxial border, which he identifies with the 
acromial process of the Monotreme scapula, and marks by the letter 
e. This process is separated by a deep notch from the glenoidal 
region of the bone; and above this process there is a long and deep 
emargination of the preaxial border (4 of the figure), superiorly to 
which the distal extremity of the bone is expanded. Now from the 
absence of any other process between that marked e and the distal 
expansion of the bone, as well as from the general similarity in the 
position of the process in question, I am inclined to consider that 
its identification with the acromial process of the Monotreme scapula 
is in all probability correct. If this be so, the pectoral girdle of the 
Anomodonts will differ from that of the Monotremes in that the 
precoracoid—which I regard as the representative of the so-called 
epicoracoid of the latter—extended upwards to join the acromion. 
In plate Ixix. figs. 5, 6, of his ‘Catalogue,’ Sir R. Owen figured 
a portion of the right side of a smaller pectoral girdle, which I have 
reason to believe belongs to the genus Péychosiagum* (Ptychognathus). 
Now in this specimen the scapula gives off a preaxial process for 
articulation with the precoracoid, which is clearly homologous with 
the one termed acromial in the preceding specimen, and is so lettered 
by Sir R. Owen. This acromial process differs, however, from that 
of Dicynodon in that it is separated only by a groove on the ventral 
aspect of the bone from the glenoidal region. Above this acromial 
process there is a shallow notch, on the dorsal side of which there 
occurs a projection which is shown by other specimens to be the 
distal extremity of the supraglenoidal portion of the preaxial border 
of the bone. The relations of these two processes are well shown in 
the right scapula of Ptychosiagum orientale represented in Plate LV. 
fig. 2, where it is quite clear that the upper or supra-acromial 
process 6 corresponds to 4 of Owen’s figure. In redescribing the 
Owenian specimen in the ‘ Phil. Trans.’ for 1888, p. 492, fig. 1, 
Professor Seeley correlates the process 6 with the acromion, not 
mentioning, however, what he would regard as the acromion in 
the scapula of Dicynodon, where, as we have seen, there is no process 
in the same position as , or giving any reasons for his rejection of 
the determination of Sir R. Owen. Now it will be quite evident 
from the comparison of figs. 1 and 2 of Plate LV. that the processes 
marked a and 6 are homologous with one another, and consequently 
that a represents the one identified with the acromion in Dicynodon. 
In describing, however, the scapula of Platypodosaurus (Quart. 
Journ. Geol. Soc. vol. xxxvi. pl. xvii. fig. 1) Sir R. Owen wrongly 
identified the supra-acromial process (e of his figure) with the 
acromial of Dicynodon, regarding the true representative of the 
latter (f of his figure) as a portion of the glenoidal region ; whereas 
it will be evident from a comparison of Oweu’s figure with Plate LV. 
that his e corresponds with 6 and his f with a of the latter, which 
we have shown to be the acromial of Dicynodon. 
If, therefore, the process in the scapula of Dicynodon with which 
the precoracoid articulates is rightly identified with the acromial of 
1 T have proposed this namein place of Ptychognathus, which is preoccupied. 
