176 CRETACEOUS AND TERTIARY FISH. 



to cranium or ossified with it. Coracoids normal, hypercoracoid 

 with median foramen. Pectoral actinosts normal, 3 or 4, hour- 

 glass shaped, longer than broad. Vertebrae from 24 to 100,. 

 usually numerous in pelagic, extra-tropical and fresh-water 

 forms. Scales variously cycloid, ctenoid, sometimes rough or 

 wanting, also small or large. Lateral line various, generally 

 regularly arched, sometimes wanting. Dorsal fin various, spinous 

 portion usually present, sometimes absent. Anal usually like 

 rayed dorsal, spines present or absent. Caudal usually lunate, 

 various, sometimes absent. Pectorals usually well developed. 

 Ventrals sometimes rudimentary or absent, generally present, 

 thoracic, subjugular or subabdominal, usually with one spine and 

 five or more rays. 



This group is apparently somewhat provisional, and does not 

 seem to have been exactly defined, though two series of families 

 have generally been admitted, as the Scombroidea and the Per- 

 coidea, comprising a vast army of living fishes typified by the 

 mackerels and perch, respectively. A few remains have been 

 found in the New Jersey Cretaceous, representatives of each. 



Family ISTIOPHORID^. 



THE SAIL FISHES. 



Body elongate, much compressed. Caudal peduncle with two 

 fleshy crests or keels. Bones of upper jaw consolidated into a 

 sword, which is roundish on edges and spear-like, shorter than 

 in the sword fishes. Teeth in jaws small, persistent and granular. 

 Gills reticulated as in sword fishes. Vertebrae 24, elongate and 

 hour-glass shaped. Neural and haemal spines flag-like. Ribs 

 well developed. Air-vessel very large, sacculate, of many sepa- 

 rate divisions. Intestine short, straight. Body covered with 

 elongate scutes. Dorsal single or divided into 2 contiguous parts, 

 first much longer than second, fin-rays distinct, first rays dis- 

 tinctly spinous. Anal divided. Last dorsal and anal rays suc- 

 torial. Ventrals attached to pelvic arch, each with one or two 

 rays. 



