24 Fourth occurrence of the Argentine 



mencement of the anal fin : between the anterior commence- 

 ment of anal and base of caudal twenty-four; but between 

 the eighth and ninth from the caudal fin, there is a space 

 where a spot appears to have been obliterated. 



About midway between the anterior commencement of the 

 dorsal and base of caudal, but rather nearer the latter, there 

 is a slight elevation, where, apparently, the fleshy fin has its 

 origin ; but in the specimen under description, it is scarcely 

 perceptible, being, even with the aid of a lens, only like a 

 slight membranous ridge. 



The formula of the fin rays appears to be D. 9. P. 17. V. 8. A. 20. C. 18' 



Mr. YarrelPs formula is D. 9. P. 17. V. 8. A. 15. C. 19' 



Mr. Yarrell remarks, " the figure of this fish, referred to in 

 Risso's work, represents the anal fin as containing many more 

 rays than are represented in the figure by Pennant." The 

 fish obtained by me possesses more anal rays than Pennant's 

 would appear to have had, judging from the figure which he 

 has published. 



Length of head compared with whole length of fish, as one 

 to four : diameter of eye to length of head, as one to three : 

 first dorsal fin commences midway between end of nose and 

 tail : depth of body to whole length of fish, as one to five and 

 a half : nostrils double, situated in a depression midway be- 

 tween the eye and centre of intermaxillary bone. The oper- 

 culum is extremely large, and appears to be developed at the 

 expense of the pre-operculum, which is very small, and joins 

 the former by a straight moveable suture, running in a line 

 perpendicularly downwards, from the posterior margin of the 

 orbit ; it forms an obtuse-angled triangle, with the obtuse an- 

 gle pointing downwards and backwards : the sub-orbital bone 

 occupies nearly the anterior inferior half of the orbit, and is 

 of a beautiful argenteous lustre, like the operculum. There 

 are five oval spots, forming a fan-shaped figure, occupying 

 the space between the anterior edge of the superior maxillary 

 bone, and the anterior inferior angle of the pre-operculum, 

 beneath the sub-orbital bone, and distinctly seen through the 

 transparent intermaxillary bone, which is very large. There 

 is one gutta upon the pre-operculum, at its anterior inferior 

 angle, and the appearance of another at the anterior inferior 

 angle of the sub-operculum : there is no appearance of bran- 

 chiostegous rays whilst the opercula are closed. 



The sides of this elegant little fish are of the most resplen- 

 dent argenteous lustre ; the gutta are of a dense opaque white, 

 and round their margin, especially along the sub-caudal series, 

 there is a steel-blue tinge, giving that part of the body a very 

 beautiful appearance. The upper abdominal series have an 



