NOTES ON THE SALMO SALAR SPECIMEN—-MORROW. 165 
The next bone we meet has its anterior edge divided, that is, 
it is Y shaped, so as to admit between its points the passage 
of the notochord, together with its protecting tissues, and the 
posterior edges of the saddle bones nearly touch the points of 
this bone. Its posterior or outer edge is united, but in a younger 
speciinen would probably be found as two separate bones. This 
bone is of the same shape, but about half the size of the Y shaped 
bone to be noticed in the ventral aspect of the spinal column 
I have thus reached the dorsal extremity of the spinal column, 
not including the spongy centrum to which the fourth or upper hy- 
pural bone is attached, and which makes, if included, 60 vertebree. 
Spinal Column, Ventral aspect—Ribs. 
Cidé2. There are no ribs on the Ist and 2nd centra, these being 
so situate as not to require them, but there are their representa- 
tives in the shape of processes. 
Ist pair on 3rd. From the 3rd centrum, at its lower edge 
spring the first pair of ribs, which are somewhat crooked in 
shape, and naturally shorter than the others. They are com- 
paratively round bones, and in length from articulation to point 
2* inches. 
C. 4. The second pair of ribs, measured in a direct line, that is, 
not following their curve, are 2? inches in length and slightly 
deeper measured transversely fen they are laterally, and taper 
to a point. 
0.5. The third pair are 34 inches long. 
C. 6. The fourth pair are 3? inches lee 
It is not necessary to give ee lengths i the remainder of the 
ribs, but it may be remarked that I find in the salmon, that the 
first two pair of ribs may be termed short, and that from 
and including the 3rd pair, to and including the 13th pair, they 
are of much greater transverse than longitudinal diameter, de 
creasing in the length of the transverse breadth as they succeed 
each other posteriorly oadest ribs. 
The remaining ribs are widest at their attachment and gradually 
decrease in size towards their points. 
C27. At the 25th pair of ribs on the 27th centrum are a pair of 
