ON MALFORMED TROUT FROM SCOTTISH WATERS 95 



i. Trout from Loeh-na-Maoraehan. 



The notion is widely spread that all the trout which occurred 

 in Loch-na-Maorachan, for I understand they have now altogether 

 disappeared from the lake, were docked-tailed, but this is not the 

 case, however abundant the malformed examples may have been. 

 I have now two specimens from this locality before me, which have 

 been given to the Museum by Mr. Harvie-Brown, in both of which 

 the caudal fin is perfectly normal. The larger of these measures 

 sixteen inches in length, and in general appearance resembles the 

 so-called Salmo ferox. All its fins are exceedingly well developed 

 and normal in their structure; the ray-formula is, — D. 14, A. 12, P. 

 13, V. 9. The smaller specimen, represented in Plate III, Fig. 1, 

 reduced to one-half, measures twelve inches in length, and in the 

 development and structure of its fins presents nothing in the least 

 abnormal, save that their rays are rather fewer than usual, and those 

 at the anterior margin of the left pectoral show a peculiar twist, 

 suggestive of some injury sustained at an earlier period of the life 

 of the fish. The fin-ray formula is here — D. 12, A. 10, P. n, V. 7. 



In Plate III, Fig. 2, is represented, reduced to three-fifths, a 

 typical specimen of the Docked-tailed Trout from Loch-na-Maora- 

 chan, the same individual of which in 1872 I gave a small outline 

 figure. The specimen is now in the Museum of Science and Art. 



The length of this specimen is ten inches. All the fins look 

 rather small, but the most striking feature is the conformation of 

 the caudal, which is very short, rounded off above and below, and 

 with the hinder border thick and stiff. In this specimen there is 

 also a slight angular projection or blunt point rather below the 

 middle of the posterior margin, as in the acuminate form figured by 

 Mr. Thomson. In Plate V, Fig. 3, a dissection of the left side of 

 the tail is shown, slightly enlarged, which renders the real nature of 

 the abnormal condition perfectly clear. The tail fin here is seen to 

 be composed in all of 42 rays, of which 13 above and 11 below 

 are as usual short, and except the hinder two in the upper, and 

 the hinder one in the lower series destitute of transverse articula- 

 tions. One of them, near the middle of the fin, is evidently 

 composed of two ordinary rays fused together at their proximal 

 ends. The 18 long middle rays, forming the mass of the caudal 

 expansion, proceed in the usual straight and diverging manner to 

 near the hinder border of the fin, when the extremities of the rays 

 above and below become suddenly bent downwards and upwards 

 respectively, thus converging towards the angular projection of the 

 posterior margin already noticed. Nor do these rays end in the 

 fine and slenderly dichotomising manner characteristic of the normal 

 fin, but their bent and somewhat contorted extremities are thick 

 and coarse, and their transverse articulations are much reduced in 

 number. In some cases one of the branches resulting from the 



