96 ANNALS OF SCOTTISH NATURAL HISTORY 



primary bifurcation of the normal portion of the ray stops altogether 

 short where the stunting of the fin commences ; in other cases the 

 two branches unite once more at their abnormal extremities, and 

 still more remarkable is the fact that at three different portions of 

 the margin of the fin the extremities of several rays are actually seen 

 to become fused together into one piece. 



The anal fin in this specimen is also seen to be rather stunted 

 in its dimensions, and, instead of presenting the normal somewhat 

 triangular figure, is rather rounded acuminate in shape. It is 

 composed of 13 rays as shown in Fig. 4, of which the third to the 

 ninth inclusive, counting from the front, are abnormal. The apex 

 of the fin, directed downwards and backwards, is supported by the 

 extremity of the eighth ray, towards which the ends of the third, fourth, 

 fifth, sixth, and seventh rays converge backwards, and that of the 

 anterior division of the ninth converges forward. The extremities 

 of these rays are thick and coarse, and those of the fifth and sixth 

 are fused together. 



The pectoral of the right side is small for the size of the fish, 

 measuring only i\ inch in length, and being contained 2\ times in 

 the distance between its origin and that of the ventral of the same 

 side, and 1^- time in that between the posterior margin of the orbit 

 and the angle of the gill-cover. It is acuminate in form, and 

 contains only 13 rays, 14 being the usual number in normal trout. 

 The second ray is here the longest ; the third has a coarse extremity, 

 in which the branches originating from its primary bifurcation again 

 unite ; the fourth and fifth rays have also abnormal extremities, 

 which bend in towards each other and nearly fuse. After the sixth 

 ray, which is also slightly affected, the rest are normal in structure 

 and aspect. The pectoral of the left side is also very similarly 

 affected, there being a strange convergence towards one point of 

 the abnormal extremities of the second, third, and fourth rays. 



The ventral fins were in this specimen normal as regards the 

 nature of the rays, but showed a very remarkable want of symmetry 

 as to size. That of the right side was perfectly normal in size and 

 development, measuring \\ inch in length, and containing the usual 

 number of 9 rays. But the left measured only one inch in length, 

 and in it only 5 rays could be counted. 



The dorsal fin presented nothing unusual in its appearance, and 

 contained the very common number of 13 rays. 



In Plate V., Fig. 2, is represented the caudal extremity of another 

 and smaller specimen from Loch-na-Maorachan, in which, as will 

 be seen, the maldevelopment of the extremities of the fin-rays has 

 not gone to so great an extent. In all the trout from Loch-na- 

 Maorachan with malformed tails which I have seen, the condition 

 of this fin is essentially the same. The rays are abnormally 

 shortened, are coarse at their terminations and deficient as to 



