80 ME. F. DAT ON THE HEBRIDAL AK GENUINE. 



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 sphyrcena, Linn., 

 and A. hebridica. Yarrell, 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. sphyrcena is said to have only 12. 

 If so great a variation as 6 can occur 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-^ (this should be 

 5J). 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 8 of total length. British Museum. 



„ Norway .. 6 ,, ,, 1 „ 8 „ Collett. 



„ Bute 6£ ,, „ 1 „ h\ „ Yarrell. 



„ N. Zealand 69 „ ,, 1 „ 7 „ Clarke, 



,, ? 7 ,, ,, 1,, 1\ ,, British Museum. 



„ Nice 7"3 ,, „ 1„ 6£ ,, British Museum*. 



„ Norway ...8£ „ ,, 1 „ 6 „ Collett. 



,, Skye 9£ „ „ 1 „ 6£ „ Day. 



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

 Yarrell's, wherein he found the height as 1 in 5-J, 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* 

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



