APPENDIX. 407 



incurved to the touch; gill aperture large, the membrane of seven 

 rays; vent nearest the head, and placed beneath the base of the pectoral 

 fins ; back with four long tubercles beneath the skin, commencing above 

 the eye, and followed by four movable recumbent, short spines, all placed 

 before the dorsal fin ; dorsal fin commencing nearest the tail, between the 

 ventral and anal fins, pointed or slightly falcate at the forepart, and very 

 narrow behind— it reaches to the base of the tail — the first ray short and 

 spinous, the rest forked, the third ray the longest ; pectoral fin long, greatly 

 falcated, and reaching much beyond the vent ; ventral fin rather before the 

 pectoral, very minute, having six branched crisped rays, placed immediately 

 before the vent; anal commencing rather before the dorsal, of the same 

 shape, and terminating in a line with it : the first ray spinous, the rest 

 branched ; caudal deeply forked. Lateral line as in P. Browniij length 

 from one to two feet. 



ARGYRIOSUS Setlfer. 



The first dorsal fin with four connected rays_, the first 

 and fourth very shorty the second and third the long- 

 est ; and two free spines placed before the anal fin. 

 Argyreiosus Vomer. Cuv. et Valeric, pi. 255. 



"We are again obliged to advert to the partial and often the 

 superficial examination with which nearly allied species have 

 too often been regarded by the authors of the Hi&t. Nat. des 

 Poissons ; an imperfection which we can only account for by 

 nearly all their descriptions having been made from preserved 

 specimens ; and by supposing that these eminent writers, not 

 unfrequently, have been absolutely overwhelmed with their 

 materials. However this may be, we have no doubt that the 

 opinion they express, of there being but one species of their 

 sub-genus Argyriosus, is equally erroneous with that which 

 regards the genus Cepola and the Platysomus Brownii. I 

 can only describe one of the present group from personal 

 knowledge ; but if the figure given in Spix's Brazilian 

 Fishes is correct, it is, notwithstanding it has been called the A. 

 vomer, a third species. The fragile nature of the filaments on 

 the first dorsal, and of the articulated rays to the Ventral fins, 

 renders any distinctions drawn from these parts very objec- 

 tionable ; but the sharp spiny prickles and hard rays of the 

 dorsal fin and back are always permanent, and I believe re- 

 markably constant in their relative size and number. 



Not having seen the species, which I shall now distinguish by the specific 

 name of Setifer rather than that oi vomer (a term altogether objectionable^, 

 it will be useless to repeat Cuvier's description, except in reference to the 

 first dorsal fin and the detached spines. Of the first he observes, that it has 

 eight rays, four of which are free, and assume the appearance of spines. Of 

 the four others which are in front, and connected by a membrane, the first 

 and the last are very short; the second remarkably long and terminated in 

 a filament, while the third is about three times the length (according to 

 his figure), of the very short spines which follow it. He also says that 

 there are, between the anal aperture and the anal fin, two fine and 

 slender spines. We leave out some minor distinctions, such as the 



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