Jordan and Evermann. Fishes of North America. 731 



Ventral fins large, posteriorly inserted, also used as organs of flight. Air 

 bladder very large. No pyloric cceca. Species numerous in all warm seas, 

 living mostly in the open water and swimming in large schools. The 

 species are largely cosmopolitan and any of the existing forms may be 

 expected to be found within our limits.* (<faotrof, sleeping outside, the 

 ancient name of a certain fish, probably a Blennius, which was supposed 

 to come out on the beach to sleep at night ; it remains out in the Fucus 

 when the tide goes down). 



EXOCCETUS: 

 . Anal fin long, its base a little less than that of the dorsal, its first ray nearly opposite first 



ray of dorsal; rays of anal 11 to 12. 

 1. Second ray of pectoral simple (as well as the first); third ray divided; fourth and fifth 



rays longest. 



c. Second ray of pectoral about as long as first ray; ventral fins inserted midway 



between posterior margin of eye and base of caudal (i. e., end of last caudal 



vertebra). EXSILIENS, 1080. 



cc. Second ray of pectoral about half longer than first; ventral fins inserted midway 



between middle of preopercle and last caudal vertebra. EONDELETI, 1081. 



bb. Second ray of pectoral divided; first ray simple; third and fourth longest. 



<Z. Origin'of ventrals midway between posterior margin of orbit and last caudal ver- 

 tebra; ventrals chiefly black. VINCIGUERR/E, 1082. 

 dd. Origin of ventrals midway between posterior margin of preopercle and last caudal 



vertebra; ventrals pale, with a dusky shade in the axil. 



e. Pectoral fins not uniform in color, dark brown, with an oblique, whitish band 

 which begins in the axil and runs obliquely backward to middle of fin; 

 edges of pectorals whitish. Pectoral fins If in length of body, their tips 

 reaching beyond dorsal. Ventrals 3% * n body, reaching about to ninth 

 ray of anal. VOLITANS, 1083. 



' ee. Pectoral fins nearly uniform brownish, without oblique pale bar. Length of 

 pectorals Ij^ in body, their tips scarcely reaching last ray of dorsal. Ven- 

 trals 3% in body, scarcely reaching last ray of anal. RUFIPINNIS, 1084. 

 CYPSELUKUS (/cviJ/cAo?, a swallow; ovpa, tail): 

 aa. Anal fin short, its base % to % length of base of dorsal, its insertion behind first ray of 



dorsal, its rays 9 or 10. 



/. Second ray of pectoral divided (first simple); third and fourth rays longest. 

 tj. Pectoral fins without round dark spots. 



/;. Ventral fins inserted about midway between pupil and last caudal vertebra, 

 f. Dorsal and anal fins without black markings; ventrals pale. 



j. Base of anal 1% in base of dorsal; pectoral If in length, reaching last 

 ray of dorsal; ventrals 2% in body, reaching last ray of anal. 



HETERURUS, 1085. 



jj. Base of anal 2 in base of dorsal; length of pectorals If in length of 

 body, their tips reaching end of dorsal fin; length of ventrale 2| 

 in body, their tips nearly reaching last ray of anal. 



LUTKENI, 1086. 



in the water, the ventrals are folded. When the action of the tail ceases, the pectorals and ven- 

 truls are spread and held at rest. They are not used as wings, but act rather as parachutes to 

 hold the body iu the air. When the fish begins to fall, the tail touches the water, when its 

 motion again begins, and with it the apparent motion of the pectorals. It is thus enabled to 

 resume its flight, which it finishes finally with a splash. While in the air it resembles a largo 

 dragon fly. The motion is very swift, at first in a straight line, but later deflected into a curve. 

 The motion has no relation to the direction of the wind. When a vessel is passing through a 

 school of tbese fishes, they spring up before it, moving in all directions, as grasshoppers in a 

 meadow. 



* For comparative descriptions of the species of flying-fishes, see Liitken, Vidensk. Meddel. 

 Nat. Foren., 1876, and Jordan & Meek, Proc. U. S. Nat. Mus., 1885. A very complete series of 

 the American forms is iu the Museum of the Academy of Natural Sciences, at Philadelphia. 



