80 S£R. E. DAT OF THE HEBRIDAL AEGENTINE. 



white on the sides; a black spot at the upper edge of the 

 orbit and a smaller one on the snout-; a darkish longitudinal 

 mark along either lobe of the caudal fin near its outer edge. 



I now propose considering whether Argentina sphyrcsna, Linn., 

 and A. hebridica, Tarrell, are or are not identical, and which 

 Collett, as I believe, with good reason states they are. Valen- 

 ciennes gives the formula thus : — 



Argentina sphyrcena D. 10. A. 12. V. 10. P. 12. 



A. hebridica D. 11. A. 12. V. 11. P. 14. 



But these numbers evidently are subject to great variation; 

 and no undoubted criterion can be deduced from the number of 

 fin-rays or scales. Nilsson found from 14 to 20 caecal append- 

 ages in A. hebridica, whereas A. sphyrcsna is said to have only 12. 

 If so great a variation as 6 can oceiir in one undoubted species 

 (especially as the present example had only 5 long ones), it would 

 be hazardous to consider that these variations in number are suf- 

 ficient to constitute distinct species. 



The principal difference pointed out in the British-Museum 

 catalogue is that in Argentina sphyrcena the height of the body is 

 8 in the total length, while in A. hebridica it is 5-g- (this should be 

 5|-). The following are the proportions of some I have examined 

 or obtained the accurate dimensions of, as Collett has stated that 

 the proportionate length to height varies with age ; fractions are 

 omitted if very trivial : — 

 from Sicily 5 inches long, height 1 in 



„ Norway ...6 ,, 



„ Bute 6£ „ 



„ N. Zealand 69 „ 



„ ? 7 



„ Nice 7-3 „ 



,, Norway ...8£ „ 



„ Skye 9£ „ 



There can be no doubt but that my Skye example agrees with 

 Tarrell's, wherein he found the height as 1 in 5|-, but does not dis- 

 tinctly say whether his specimen was a skin or in spirit. Valen- 

 ciennes states his examples of the same species were 1 in 8 of 

 the total length, or similar to what he found existed in A. sphy- 

 rcena. As we see in those examples which have been preserved in 

 alcohol, some the height of whose body is 6, others 6|, 7, or 8, in 

 the total length, it is evident that this proportion varies, and 



* The length of the caudal fin is deduced from the average of other speci- 

 mens, as this fin is often broken in museum examples. 



1 in 8 of to 



tal length. 



British Museum. 



1 „ 8 



„ 



Collett. 



1„ 5| 



„ 



Yarrell. 



1„ 7 



„ 



Clarke, 



1„7£ 



,, 



British Museum. 



1„ $i 



„ 



British Museum* 



1„ 6 



„ 



Collett. 



1„ 6£ 



,, 



Day. 



