NOTES ON THE SALMO SALAR SPECIMEN--MOItROW. 167 



producing the beautiful outline of the posterior part of the 

 salmon. 



G. 36. On this centrum (the first of the caudal centra proper), 

 the spinous processes are 1-| inches in length, and attached pos- 

 teriorly for fg of an inch is a bone or bones having an extreme 

 divergence from the normal angle, which might be taken for a 

 pair of ribs. The sp. processes, of which mention has been made, 

 are all of the same character as the dorsal and other spinous 

 rays, that is formed of two bones, one springing from each side 

 of the arch and united moie or less strongly, as the age of the 

 fish may be. This bone, or if you choose pair of bones, are an- 

 chylosed and appear as one, their length from the junction with 

 the sp. processes is 2? G of an inch ; in the skeleton before you the 

 separation of their ventral ends is a consequence of their dryness. 

 An examination of young fish will show you that this bone (or 

 bones) originates in a different way from the ribs ; looking at 

 this skeleton of what may be called a mature fish it appears to 

 be a single bone and to have originated and grown from the end 

 of the spinous process, passing and uniting with its next posterior 

 ventral spinous ray having its ventral end attached to the end of 

 the third interspinous fin bone of the anal fin which it slightly 

 overlaps, say \ inch on the outer and right hand side. In a young 

 fish you will find the spinous processes, but the long bone is 

 merely a short straight bone lying between the processes on the 

 36th and 37th centra ; in the skeleton of the young fish before 

 you the bone does not touch the posterior edge of the 36th sp. 

 process, but is about i\ of one inch from it, and it just touches the 

 anterior edge of the spinous process of the 37th centrum, the end 

 of which it does not reach by nearly half an inch ; it is therefore 

 most probable that it grows from a centre each way, that is dor- 

 sally and ventrally, but that its growth is most rapid towards its 

 ventral extremity. 



C. 37. On this centrum (counting the ribs as sp. processes) the 

 35th ventral sp. ray is attached, and is the first ventral sp. ray 

 having the usual form ; it is 1^ inches in length, its ventral an- 

 terior extremity is united by cartilage to the bone just mention- 

 ed as springing from the end of the 34 sp. process, the great 



