ACANTHOPTERYGII. 149 



IsTioPHORus, Lacep. Notistium, Herman. 



The beak and caudal crests of a Tetrapturus, but the dorsal is 

 Tery high and serves them for a sail when swimming; their long 

 and slender ventrals are composed of two rays. 



There are several imperfectly determined species, one of 

 which inhabits the Indian Ocean, Scomber gladius, Broussonet, 

 Acad, des Sc. 1786, pi. x; Xiphias velifer, B\.,^chn.; Xiphias 

 platisterus, Shaw, IV, part II, p. 101, and was long ago de- 

 scribed.(l) 



All the fishes of this genus attain a very large size. 



Centronotus, Lacep. 



A genus of Scomberoides characterize.d by the spines, which, in 

 the Acanthopterygii in general, form the anterior portion of the 

 dorsal, or a first separate dorsal, but in them are free and uncon- 

 nected by a common membrane; they all have ventrals. They are 

 subdivided as follows: 



Naucrates, Rafin. 



Free dorsal spines; body fusiform; a carina in the sides of the 

 tail as in the Tunny, and two free spines before the anal fin. 



The common species, or the Faufre of the sailors of Provence; 

 Gasterosteus ductor, L. ; Scomber ductor, Bl., 338, is blue with 

 broad vertical bands of a much deeper blue. The vulgar name 

 o^ Pilot-fish owes its origin to the fact, that it follows vessels to 

 seize upon what may fall from them; and as a similar habit is 

 observed in the Shark, it has been said that the former acts as 

 a guide or pilot to the latter; it is not above a foot long. 



A black species is found at Brazil, the Ceixupira, Marcgr., 

 158; Scomber niger, Bl. 337, which is eight or nine feet in 

 length. 



Elacates. 



The general form of a Naucrates, and its free dorsal spines; but 

 the head is horizontally flattened, and both the caudal carina and the 

 free spines before the anal are Avanting.(2) 



(1) It has also been figured by Nieuhof, App.; Willugb., App., pi. V, f. 9, by 

 Renard, I, pi. 34, f. 182, and 11, pi. 54, f. 233; by Valentyn, No. 527. The Gue- 

 bucu, Marcgr. 171, hardly appears to differ from the species of India, ill. 345, is a 

 falsified copy of a figure of Pr. Maurice, which differed much less from that of 

 Marcgrave. 



(2) El motta, Cuv., Pedda mottah, Russel, 153; El. amertcana, Cuv., Centra- 



