NOTES ON THE SALMO SALAR SPECIMEN — MORROW. 169 



ceding it. Its breadth is about equal throughout. It has a 

 somewhat blunt ventral end, and it is 1^ inches long ; in the 

 slight hollow between this and the 49th sp. ray, is attached the 

 beginning of the caudal muscle which envelopes the short rays of 

 the caudal fin. 



C. 54- Opposite the end of the 52 sp. ray begin the short ven- 

 tral rays of the caudal fin at right angles to the posterior edge of 

 the 56 centrum. The character of the attachment of the ventral 

 sp. rays appears to change with this centrum, their dorsal ends 

 have spread and are in one sense flattened and seem to have an 

 articulated surface as may be noticed by looking at the 52nd, 

 53rd, 54th, 55th, and 56th ventral sp. rays on this skeleton. The 

 posterior edge of this ray (52) is anchylosed with the anterior 

 edge of 53 for about two thirds of their length from their dorsal 

 towards their ventral extremities. 

 C. 55. The 53 sp. ray. \ these bones are more or less perfectly 



56. " 54 " Vanchylosed, their shapes are so irregular 



57. " 55 " J that only a drawing (which I regret to 

 say I am unable to makej or reference to the skeleton can give 

 you a clear understanding of them. 



58 — 56th sp. ray. This ray is anchylosed on its anterior edge 

 to the 55th sp. ray for about half its length, say f of an inch, and 

 on its posterior edge rather more than half its length, say half 

 an inch from its foramina* towards its ventral extremity, to the 

 lower hypural bone ; on its ventral end it is free, say ' { s of an inch. 

 In shape this ray differs from all the others, at its dorsal end it 

 is somewhat triangular, having a cup-like projection on each 

 side at its junction with its centrum, and its ventral end is in- 

 cluded in a cartilaginous rim which passes round the bones 

 forming the termination of the column. This bone, together 

 with the two saddle bones on the dorsal aspect of the spine, ap- 

 pear to me to be the representative of the pelvic hones in 

 mammals. 



* The foramina in this bone are for the passage of the blood vessels. The superior in this speci- 

 men passes to the left, the inferior to the right side, each opening into a sack or sinus having a 

 communicating foramen which lies between the first lower and second lower hypural bones. There 

 is also a foramen at the junction of thi.s bone with the anterior edge of the lower hypural in this 

 specimen, of considerable size, in others smaller in proportion. 



