1870.] HANCOCK AND HOWSE—MARL-SLATE PROTEROSAURI. 569 
sible to make out the parts, or to say whether or not they are pro- 
vided with the long characteristic spinous processes of P. Spenert. 
Indeed it is difficult to determine the number of joints, though 
twelve can be counted. As, however, there are fourteen or fifteen 
pairs of ribs, there must be at least as many dorsal vertebre. It 
would still seem, nevertheless, that they are not so numerous in this 
species as they are in P. Spener2, in which we have seen there are 
seventeen or eighteen dorsal vertebrae. But it is quite possible, in- 
decd it is likely, that there are more rmbs than we have been able to 
enumerate, in which case we have underestimated the number of 
the vertebra ; and the two species may be found to agree in this 
particular more closely than is apparent. It is equally impossible 
to ascertain the character and exact number of the cervical vertebre ; 
but as six or seven lie scattered about in front of the trunk, it would 
seem that this species may have seven, the number of the neck-ver- 
tebree of P. Spenert according to Meyer. All that can be said about 
the caudal vertebree is, that the traces of their remains seem to indi- 
cate that the tail, when perfect, must have been of considerable 
length. About 2 inches of the distal extremity is determinable ; 
and as about the same length of the proximal portion seems to be 
broken away, the tail, when complete, must have been longer than 
the trunk, which is nearly 3} inches in length. 
The ribs lie, as we have already said, spread out in their natural 
order on each side of the vertebral column, and fourteen or fifteen pairs 
can be enumerated ; but there is some difficulty in determining the 
precise number. They are well and regularly arched from end to end, 
and are moderately and nearly equally thick throughout. Towards 
the proximal end they are a little flattened, and terminate in a slightly 
enlarged simple head of a triangular form. The distal extremity is 
abruptly truncated, but is not flattened and widened to the same 
degree as the ribs of P. Spenert; neither are the ribs so decidedly 
grooved as they are in that species, but are, on the whole, more 
eylindrical. The ventral ribs appear to have been numerous and 
comparatively stout; they lie pressed in between the vertebral ribs 
near to the spinal column, but their relative number cannot be 
ascertained. The longest vertebral ribs are near the centre of the 
trunk; here they are ¢ inch long, measured along the chord; they 
shorten a little before and behind to about {4% inch in front and 54 
behind. 
Both the coracoids are well preserved, particularly the left, which 
lies nearly in its natural position at the left side on the fore part of 
the trunk. The right coracoid is removed a short distance in front. 
They are stout discoidal bones 2 inch in diameter, with a deep, wide 
notch, apparently on the posterior margin, forming the glenoid cavity 
for the articulation of the humerus. At the inner margin of the 
notch there is an elevated boss; and from thence to the front mar- 
gin there is a widish ridge indicating perhaps the compound nature 
of this bone, which is most likely composed of both the coracoid and 
scapula, the glenoid cavity being as usual at the junction of the two 
elements; but there is no distinct trace of a suture. There is a 
VOL, XXVI,—PART I, 28 
