174 NOTES ON THE SALMO SALAR SPECIMEN — MORROW. 



fin from anterior fco posterior edge, (rays only) three and three- 

 quarters inches, and including the end of the last interspinoua 

 bone four and a quarter inches. 



Adipose Fin. 



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 

 attachment 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, which is somewhat 

 thickened and of firmer structure (more like a cord), where it 

 anpears, 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 bring 

 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 of the 54th spinous ray begins the upper or 

 dorsal portion of the muscle of the tail rays: this beginning 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 lino 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 h 9th are single at their insertion as well as at 

 their dorsal ends. 9 is one and a half inches long. 



