NOTES ON THE SALMO SALAR SPECIMEN--MORROW. 173 
15 and last intersp. fin bone is 1; inches in length. It has a pro- 
longation posteriorly for the attachment of the last single together 
with the double fin ray, and also for the strong fibrous attach- 
ment which connects it with the dorsal muscle. 
The fin-rays of the dorsal fin are in number 15. By some they 
would be counted as 14, but further on I will give the reason for 
counting them as 15. 
Ist Ray. This ray is so small as to be easily overlooked in 
young specimens. In this one from its root or articulation with 
its intersp. bone it is five-sixteenths of an inch in length : the point 
of it reaches only through the skin, but it is a true ray, having 
its bony regular articulation just above the anterior face of the 
short one of the triple bone. 
2nd ray. The second ray is five-eighths of an inch, and 
3rd ray. the third ray is one and three-eighth inches in length, 
these first three rays are covered or as it were included in the 
integument as one ray. 
4. The fourth, or first ray having its full length, is three and 
seven-eighth inches from articulation to point; divided at its 
ventral extremity to form its articulation on each side of the in- 
terspinous bone, as are all the fin-rays. 
5 to 10. are all of the same type gradually decreasing in length: 
to ten, which measures two and three-eighth inches. 
1, The eleventh ray is two and one-eighth inches. 
12. The twelfth ray is one and seven-eighth inches. 
18. The thirteenth ray is one and five-eighth inches. 
14 & 15. Although apparently so closely united, 14 & 15 are 
separate fin-rays, having each an articulation, that is, the 1/th ray 
is set within the 14th. They are attached as before stated to the 
posterior extremity of the 15th intersp. fin bone, and if the first 
three short rays are to be counted, then should these rays be 
counted as two, for though they are articulated to one base, yet 
each is a complete ray. 
The height of the interspinous bones of the dorsal fin, to the 
junction of its fin-rays, from the centre of the vertebra at right 
angles to the anterior edge of the fin, is three and a half inches ; 
at. the posterior edge, three and a quarter inches ; length of dorsat 
