18 MR. F. DAY ON RACKS AND [Jan. 15, 



opportunity of examining along the coast of Devonshire during the 

 past half-year. 



The first specimen I propose describing is a hybrid between 

 Salmo salar and S. levenensis. On November 25th, 1879, aa 

 detailed by me previously (Proc. Zool. Soc. 1882, p. 751), a man 

 arrived at Howietoun, sent over from Stirling by Mr. Napier, with 

 some Salmon-milt obtained the previous night, and this was employed 

 for the purpose of fertilizing some eggs from a 4-year-old Lochleven 

 Trout. It is necessary to draw attention to the fact that the milt 

 came from the Salmon, as the size of the spermatozoa is such as to 

 generally render impregnation of Trout-eggs difficult in the natural 

 state. But here the milt had been brought in a bottle packed in 

 snow or ice, and although the cold may have caused tbe size of the 

 spermatozoids to contract, it appears to me more probable that the 

 large eggs of these Trout possessed a comparatively large micro- 

 pyle. Perhaps, as we find parr full of milt during the Trout- 

 spawning season, the size of the spermatozoids preclude their impreg- 

 nating the majority of the Trout-eggs which would be on the beds ; 

 for, although it has been computed that the absorbing powers of the 

 ova extend over 30 minutes, the period during which the spermato- 

 zoids are alive in water is about 2| minutes, and it is probable that 

 for such a time the male Trout would hardly permit a parr to inter- 

 fere with the redd. 



One of the progeny of the above experiment, 1 1 inches in length, 

 was captured in my presence at Howietoun, November 14th, 1882, 

 and I subsequently described it in full (/. c). In the island-pond 

 two years since some more (which were the smallest fish) were placed, 

 and when this pond was drained on November 28th, 1883, several 

 were obtained. I sent three to the Economic Fish Museum at 

 South Kensington ; one I retained for personal examination. The 

 specimen is on the table, and, although a year older than the one 

 I described in 1882, is of the same length, while the others were 

 slightly smaller ; and investigations into the rapidity of the growth 

 of these fish will form a subject for inquiry next year among those 

 which still remain. 



B. x. D. 12 (|). P. 13. V. 10. A. 11 (|). C. 19. 



L. 1. 1 14. L. tr. 24/32. Ctec. pyl. 69. 



inches. 



Total length of specimen . . 11-0 



Length of head . . 2*0 



Length of pectoral fin 1-5 



Distance from snout to base of dorsal fin 4*2 



Distance from snout to centre of base of caudal fin 9 - 



Diameter of eye 04 



Distance of eye from end of snout 0-6 



Distance of eyes apart 0*7 



Height of body 2 - 5 



Preopercle forming an almost regular curve, with but very little 

 appearance of a lower limb. Lower jaw very slightly hooked at its 



