NOTES ON THE SALMO SALAR SPECIMEN—MORROW. 169 
ceding it. Its breadth is about equal throughout. It has a 
somewhat blunt ventral end, and it is 1} inches long; in the 
slight hollow between this and the 49th sp. ray, is attached the 
beginning of the caudal muscle which envelopes the short rays of 
the caudal fin. 
C. 54. Opposite the end of the 52 sp. ray begin the short ven- 
tral rays of the caudal fin at right angles to the posterior edge of 
the 56th centrum. The character of the attachment of the ventral 
sp. rays appears to change with this centrum, their dorsal ends 
have spread and are in one sense flattened and seem to have an 
articulated surface as may be noticed by looking at the 52nd, 
53rd, 54th, 55th and 56th ventral sp. rays on this skeleton. The 
posterior edge of this ray (52) is anchylosed with the anterior 
edge of 53 for about two-thirds of their length from their dorsal 
towards their ventral extremities. 
C. 55. The 53 sp. ray. ) these bones are more or less perfectly 
D6. 5 54 § | anes their shapes are so irregular 
Oise bb Of that only a drawing (which I regret to 
say I am unable to make) or reference to the skeleton can give 
you a clear understanding of them. 
48—56th sp. ray. This ray is anchylosed on its anterior edge 
to the 55th sp. ray for about half its length, say 3 of an inch, and 
on its posterior edge rather more than half its length, say half 
an inch from its foramina* towards its ventral extremity, to the 
lower hypural bone ; on its ventral end it is free, say 5 of an inch. 
In shape this ray differs from all the others, at its dorsal end it 
is somewhat triangular, having a cup-like projection on each 
side at its junction with its centrum, and its ventral end is in- 
cluded in a cartilaginous rim which passes round the bones 
forming the termination of the column. This bone, together 
with the two saddle bones on the dorsal aspect of the spine, ap- 
pear to me to be the representatives of the pelvic bones in 
mammals. 
* The foramina in this bone are for the passage of the blood vessels. The superior in this speci- 
men passes to the left, the inferior to the right side, each opening Into a sack or sinus having a 
communicating foramen which lies between the first lower and second lower hypural bones 
There is also a foramen at the junction of this bone with the anterior edge of the lower hypura) 
in this specimen, of considerable size, in others smaller in proportion. 
