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. 



1st 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 on the triple bone. 



2nd ray. The second ray is five-eighths of an inch, and 

 3rd ray. The third ray is one and three-eighths inches in length, 

 these first three rays are covered or, as it were, included in the 

 integument as one ray. 



Jf.. The fourth, or first ray having its full length, is three and 

 seven-eighths inches from articulation to point ; divided at its 

 ventral extremity to form its articulation on each side of the in- 

 terspinous bones, 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-eighths inches. 



11. The eleventh ray is two and one-eighths inches. 



12. The twelfth ray is one and seven-eighths inches. 



13. The thirteenth ray is one and five-eighths inches. 



llf. & 15. Although apparently so closely united, 14 & 15 are 

 separate fin-ra}'s, having each an articulation, that is, the 15th 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 vertebrae 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 dorsal 



