174 NOTES ON THE SALMO SALAR SPECIMEN—MORROW. 
fin from anterior to posterior edze, (rays only) three and three- 
quarter inches, and including the end of the last interspinous 
bone four and a quarter inches. 
Adipuse Pin. 
Of the adipose fin there is little to say. Its anterior edge is 
opposite the posterior edge of the base of the anal fin, it has no 
attachinent through the dorsal muscle to the general muscular 
tissue. It appears to be an expansion of the integument, and has 
its base in the cord of the dorsal muscle, wien is somewhat 
thickened and of firmer structure, (more like a cord), where it 
appears, more so anteriorly than posteriorly. There does not 
appear to be in it anything which can be called a fin-ray. I have 
examined a number of S. salar as well as S. canadensis, with a 
good glass without discovering any trace of what might be term- 
ed.a ray, but I cannot say that the microscope would not bing 
them to view. The only difference observed by me is that while 
most are smooth and rounded off at the dorsal edge, some present 
a few of what might be termed raylets, forming a delicate 
feathered edge. 
Caudal Fins. 
At the point ef the 54th spinous ray begins the upper or 
dorsal portion of the muscle of the tail rays: this beginuing of 
the caudal fin, which is enveloped by the muscle consists of 
eleven short rays or spines, filling in and giving to the tail as a 
whole its line of beauty, strengthened by the anchylosed dorsal 
sp. rays, and adding to the propelling power of the tail. These 
short rays are all divided at their anterior ends (or V shaped) 
united on each side to the general structure, presenting at the 
dorsal edges the appearance of single rays. 
1-4. 1-4 are short and straight. 
5-6. 5-6 are somewhat curved, the 6th more pointed at its 
outer extremity than the 5th. 
7. 7 is single at its insertion and divided into two rays at its 
extremity, and from its division to outer end somewhat curved 
and pointed. 
8&9. The 8th & 9th are single at their insertion as well as at 
their dorsal ends. 9 is one and a half inches long. 
