In the genus _Exonautes_ the base of anal fin is long, as long as that of the dorsal. The species of this group, also strong in flight, are widely distributed. Most of the European flying-fishes, as _Exonautes rondeleti_, _Exonautes speculiger_, and _Exonautes vinciguerræ_, belong to this group, while those of _Cypselurus_ mostly inhabit the Pacific. The large Australian species _Exonautes unicolor_, Fig. 226, Vol. I, belongs to this group. In the restricted genus _Exocœtus_ the ventral fins are short and not used in flight. _Exocœtus volitans_ (_evolans_) is a small flying-fish, with short ventral fins not used for flight. It is perhaps the most widely distributed of all, ranging through almost all warm seas. _Parexocœtus brachypterus_, still smaller, and with shorter, grasshopper-like wings, is also very widely distributed. An excellent account of the flying-fishes of the world has been given by Dr. C. F. Lütken (1876), the University of Copenhagen, which institution has received a remarkably fine series from trading-ships returning to that port. Later accounts have been given by Jordan and Meek, and by Jordan and Evermann. [Illustration: FIG. 169.—Catalina Flying-fish, _Cypselurus californicus_ (Cooper). Santa Barbara. ] Very few fossil _Exocœtidæ_ are found. Species of _Scombresox_ and _Hemirhamphus_ are found in the Tertiary, the earliest being _Hemirhamphus edwardsi_ from the Eocene of Monte Bolca. No fossil flying-fishes are known, and the genera, _Exocœtus_, _Exonautes_, and _Cypselurus_ are doubtless all of very recent origin. CHAPTER XII PERCESOCES AND RHEGNOPTERI =SUBORDER Percesoces.=—In the line of direct ascending transition from the _Haplomi_ and _Synentognathi_, the pike and flying-fish, towards the typical perch-like forms, we find a number of families, perch-like in essential regards but having the ventral fins abdominal.