38 MARINE AND FRESHWATER FISHES 



bands of a darker hue. The Rudder-fish, or Black Pilot 

 {Pammelas perciformis), No. 49, and the Derbio, or Glaucus 

 Mackerel (Lichia glaitcd), No. 50, are two rarer forms, some- 

 what resembling the true Pilot-fish, but with relatively 

 shorter bodies, that are usually referred to the Carangidce, 

 and lead the way to the compressed, short-bodied species 

 known as the Boar-fish, or Cuckoo-fish (Capros aper), 

 No. 51. This little fish, which in shape much resembles 

 a John Dory, but rarely exceeds six inches in length, and 

 is usually coloured a bright orange-red, with occasionally a 

 variable number of darker vertical bands, is not uncommon 

 off the Cornish coast, preferring moderately deep water in 

 the neighbourhood of rocks. Though of no value as a food- 

 fish, it is a great favourite for exhibition in aquaria, its 

 quaint shape, bright colours, and habit of swimming 

 fearlessly in the middle of the water, rendering it specially 

 suited for such a purpose. It has been observed by the writer, 

 of examples imported by him from Mr. Matthias Dunn, of 

 Mevagissey, Cornwall, to the Brighton, Manchester, and 

 Westminster Aquaria, that the ordinary slow locomotion 

 of the Boar-fish, as in the case of the John Dory, is 

 accomplished solely by the screw-like undulations of the 

 soft-dorsal and anal fins. 



FAMILY XIII.— The Dory Tribe {Cyttidce). 



Body elevated, greatly compressed ; naked, or covered 

 with small scales or bucklers ; teeth, small, conical ; no bony 

 stay to the pre-operculum ; the dorsal fin composed of a 

 distinct, soft and spinous portion ; branchiostegal rays seven 

 or eight in number. 



This small marine group contains less than a dozen 

 existing species, referable to the two genera Zeiis and 



