180 Mr. T. Stock on the Genus Tristychius. 
vertebral column found in connexion with the remains of two 
spines (Pl. VII. fig. 8), the whole undoubtedly belonging 
to the same fish. This fragment has been preserved on a 
thin piece of weathered ironstone shale, and was picked up 
by myself at Carolina Park, near Edinburgh *. 
Description.—There are the remains of two spines; the 
shape of the larger is well seen, chiefly as an impression, how- 
ever, on the slab. It is 24 inches in length, a fairly large 
specimen. The cast shows that it was distantly and regularly 
striated. I can detect traces of one or two denticular impres- 
sions only. It conforms to typical examples of the species. 
This I interpret as the right pectoral spine. Slightly poste- 
rior in position and directed towards the opposite side of the 
axis are the much-broken remains of the base of a second 
spine (PI. VII. fig. 8, s). This is proved conclusively by the 
pulp-cavity, which is seen in section at the edge of the slab. 
I interpret this as the remains of the left pectoral. They were 
probably paired spines at any rate; and their position with 
regard to the axial column is in favour of their being pectoral. 
There is much difticulty, however, in disentangling the con- 
fused appearances presented on that part of the slab immedi- 
ately behind the spmes ; and at the anterior inferior angle of 
the slab some plant-remains + complicate matters, so that 
another reading could I dare say be defended. ‘The position 
of the bases of the spines (almost overlapping) with regard to 
each other shows that there has been some disturbance during 
fossilization; and the disturbance which has pushed in the 
spine s (Pl. VII. fig. 8) has also pushed outwards the two 
neural spines n (Pl. VII. fig. 8), which occupy a peculiar 
and rather misleading position with regard to the spine s’. 
On the lower front angle of the slab there are some ap- 
pearances dubiously referable to the pectoral fin (Pl. VIL. 
fig. 8,7) 
The remains of the axial-column (23 inches long) are in a 
tolerably good state of preservation. The apophysial ele- 
ments are represented by a double series of closely approxi- 
mated spines (neural and heemal), consisting of granular carti- 
lage, numbering between twenty and thirty in each row. 
They are rather better preserved on the neural than on the 
* T have found this locality, situated at the extreme western end of 
the Wardie and Granton sandstones and shales, extremely prolific in fish 
fossils. Unfortunately they are not usually in good preservation. It is 
noticeable that nearly all of the specimens collected are referable to forms 
already and commonly known from the eastern and more frequently 
worked shales. 
+ Left out in the drawing. 
