CLASS PISCES. 189 



because the prickles which, in the acanthopterygians 

 in general, form either the anterior part of the dorsal 

 or a first distinct dorsal, are in these detached and not 

 united by a common membrane ; their ventrals are 

 never wanting. They are subdivided as follows : 



Naucrates, Rqfin., 



Have, besides the detached prickles of the back, a 

 spindle-shaped body, and a keel at the sides of the 

 tail, like the tunny, and two separate prickles in 

 front of the anal. 



The common species, or the fanfre of our Pro- 

 vencal sailors, {Garter osteas ductor, Lin., Scomber due- 

 tor, Bl. 338) is blue, with wide vertical stripes of a 

 darker blue. It takes its name (Pilot-fish) from its 

 custom of following the ships to catch all that falls 

 from them, and as the shark has also this custom, 

 travellers have said that it acts as guide to the shark. 

 Its length is scarcely more than one foot. 



There is a black species, the Ceixupira, Marcgr. 158, 

 {Scomber ?iiger, Bl. 337) which reaches eight or nine 

 feet in length. 



Elacate, Cuv. 



Have the same general form as the pilots, and their 

 detached prickles on the back ; but their head is 

 flattened horizontally, and they have neither keel at 

 the tail, nor detached prickles before the anal 1 . 



1 El. motta, C. Pedda mottah, Russel. 153. ; EL Americana, C, 

 Centronotus sphwsus, Mitch. Ann. cit. Nov. I. iii. 9. which is pro- 

 bably the Gasterosteus canadensis, L., and some new species. 



