232 The Scottish Naturalist. 



reddish coloration of the dorsal and ventral edges of the tail 

 is less developed in the former than in the latter. 



In regard to the mamillaries the same progressive series oc- 

 curs. The smolt has the shortest bone, the " yellow fin" having 

 a decidedly larger structure, extending behind the middle of 

 the eye, while in the trout a still further increase in size is ap- 

 parent. Moreover, the maxillary is less ossified in the two for- 

 mer, though this is a character on which too much reliance 

 should not be placed in the discrimination of young specimens. 



The pyloric appendages show the same peculiarities. In the 

 salmon they range from 53 to 77 (Giinther). Most of the 

 Stormontfield smolts had 60. In the adult fish these caeca are 

 the favourite haunts of tapeworms and gregariniform parasites. 

 The " yellow fins," again, present a number varying from 49 to 

 57 in our specimens : while in the common trout of the Tay, 

 Ericht, Allan-water, and the mill-stream at Stormontfield, the 

 appendages ranged from 38 to 56. There is thus a gradation, 

 though the highest number given by Dr. Giinther in the case of 

 the common trout is below our reckoning. 



The peculiarities as to the fin-rays, rows of scales, vertebrae 

 and pyloric caeca, will be best explained by the following table 

 from Dr. Giinther's Catalogue of the Salmonoids. 



Dor. An. Pect. Ven. L. lat. L. trans. 



2226 



S. salar, - - 14 11 14 



S. trutta, - - 13 11 15 



19-22 



24 26 



120 ; — 



36-34 



.S. fario (Scotch), 13-14 11-12 14 9 120 27-30 



5. brachypoma, - 13 10-11 14 9 1 18-128 27-30 



The sexes in the ''yellow fins" could be made out in all 

 cases with ease. In a small specimen (about 5 inches) from 

 Stormontfield mill-stream the ova were quite visible to the naked 

 eye as minute grains ; while in the larger specimens from the 

 Allan-water, some showed considerable activity in the ovaries, 

 so that it is possible they might spawn in autumn. Most of 

 the specimens were females. 



Dr. Young asserted that he did not find a silvery coat in 

 other than sea going fish, but doubtless he meant the loose scales 

 of the young migratory fishes, since the Loch Leven trout, 

 amongst others, is an example to the contrary ; and Dr. Giinther 



