524 Prof. M'Intosh on the 



more powerful — broader at the base and hence more rapidly- 

 tapered. Unfortunately Mr. Day does not state (and this is 

 important) wliether his figure is taken from a small or a large 

 example, since the relative proportions between the length of 

 the spines and the depth of the body probably undergo changes 

 during growth. The first spine is one which even the unini- 

 tiated would call powerful. Another way of looking at the 

 comparative lengths of the spine and other parts than that 

 adopted by Mr. Day is to measure it (the spine) accurately 

 by compasses in the figure in the ' British and Irish Fishes,' 

 and then pass the compasses downward over the body, when 

 it is found that at the second sweep of the instrument the free 

 tip slightly exceeds the ventral outline. In the fresh example 

 here nearly three such steps were necessary to clear the ven- 

 tral margin. 



If the premaxillary and maxillary region in the recent 

 animal be measured with calipers, and the instrument then 

 be turned backward to the opercular margin, the observer will 

 find that two steps require to be taken to reach the latter 

 (opercular margin). If this be done in Mr. Day's figure it 

 will be found that the second sweep of the compasses exceeds 

 the opercular margin by about a fourth. The measurements 

 in the case of the "snout" and the "eye" mentioned by 

 Mr. Day give the results he states, though in his figure the 

 distance exceeds 2| (that for the larger example in the British 

 Museum) . The eye in the figures is as stated in my paper 

 when compared with the fresh example. Further, if a vertical 

 line be drawn along the posterior margin of the operculum^ 

 it will be found to approacli the first dorsal spine too closely 

 in Day's figure, thus additionally demonstrating what was 

 mentioned with regard to the head. A reference to Mr. 

 Couch's figure will also clear up the situation on this point, 

 as well as bring out the fact that the origin of the pectoral 

 is considerably in advance of a vertical line from the first 

 dorsal spine, instead of being touched by it, as in the ' British 

 and Irish Fishes.' Couch, it is true, says in his description 

 that the first dorsal begins nearly above the origin of the pec- 

 toral ; but his figure more closely accords with nature in this 

 respect. 



The relative positions of the second dorsal and the jj-nal fins 

 may vary ; but such cannot be allowed to rest on facts derived 

 from stuffed specimens. If it were so, the novelty of the 

 origin of one pectoral in front of the other could in the same 

 manner be stated of the bonito in the St. Andrews University 

 Museum. In the tunny so characteristically was the anal behind 

 the vertical line from the posterior base of the second dorsal, 



