Prof. M'lntosh's Noten on the Tunny. 329 



Yalenciennes's figure, the gape in both, moreover, being too 

 long in its antero-posterior axis. The teeth are somewhat 

 fancifully represented in all the figures, since they are much 

 less distinct in nature. The spines of the dorsal fin are all of 

 nearly equal thickness in the figure of the French authors and 

 in Day's and Yarrell's, whereas, with the exception of the 

 first, they are too thicic in Couch's. They seem to have been 

 unusually long anteriorly in the specimen figured by Day. 

 The second dorsal fin has not been well represented in any of 

 the figures, and it is much too broad and short in Couch's. 

 The awkward flattening of the back along the base of the first 

 dorsal fin in Day's figure is probably due to the taxidermist 

 and is not found in nature or in the other outlines mentioned. 

 The anal fin is also too short and broad in most of the figures, 

 and Day's outline materially differs from nature in the rela- 

 tion of the second dorsal and anal fins to a vertical line. 

 A line running vertically from the anterior margin of the anal 

 falls behind the second dorsal ; but in Day's figure it pierces 

 the dorsal midway. The upper margin of the deep groove 

 for the pectoral in a lateral view is generally seen above the 

 somewhat straight edge of the pectoral ; but this has not 

 found its way into any representation. In none of these 

 figures is the true sliape of the finlets given, for in each a 

 distinct elevation occurs in front and then a pointed process 

 extends backward nearly parallel to the outline of the body ; 

 they are, in short, unequally bifid. The figure in Day's 

 ' British Fishes ' deviates considerably from life in this 

 respect. 



In the branchial chamber were numerous specimens of a 

 Caligus, several examples bearing large tufts of Obelia getii- 

 culata, which seemed to flourish with remarkable vigour on 

 so favourable a site. The hydrorhiza in some cases covers 

 the ventral surface of the cephalothorax of the parasite with 

 an intricate web of fibres, amongst which the feet can hardly 

 be distinguished, while the dorsum of the same region is 

 entirely shaded by a dense tuft of the polyparies, which are 

 of great strength. In others the stolons spring from the abdo- 

 minal region. 



Digestive System. — The teeth appear proportionally small 

 for so large a fish ; they are slightly curved and turned 

 inward and backward. A rasp-like surface occurs on the 

 median hyoidean apparatus, and the sides of the tongue have 

 a few horny processes. The mucous surface of the roof of 

 the mouth has, in addition to the rasp-like teeth on the pala- 

 tines, numerous hardened streaks from thin ossifications of the 

 region. 



