REVIEW OF LOCAL FISHES 53 



dark mark at the base of the back fin in front is characteristic though 

 not alvvaj'^s present. In this vicinity it occurs coastwise in almost fresh 

 water where some years it is abundant. 



VII. Flyingfish, Stickleback and a variety of others 

 (Synentognathi, Thoracostraci, etc.) 



In this chapter are thrown together for the sake of convenience a 

 number of more or less unrelated species. We begin with the Billfish, 

 a long slender pencil-shaped species with wide-opening elongated jaws, 

 about equal in length, set with formidable sharp teeth. The Billfish, 

 abundant with us in summer, inhabits salt water and also enters the 

 mouths of fresh rivers and creeks swimming in small schools at the 

 surface and preying on other smaller fishes, especially the common 

 Silverside. It reaches a length of four feet but is usually much smaller 

 and is transparent green in color with silvery sides. The uncommon 

 Half -beak is a related species with the lower jaw only elongated, hard 

 and toothless, the upper jaw short and the mouth consequently small. 



HALF-BEAK 



It feeds chiefly on alga?. The Billfish has the most interesting habit of 

 launching itself out of water and skipping over the surface as might a 

 lance or spear. It is a habit shared by others of its elongate relatives 

 which are represented by numerous species in tropical waters. A com- 

 mon species with a flattened body is especially noteworthy as a leaper 

 and can cover considerable distances by turning on its side and letting 

 the air or water strike against its flattened surface. One of the most 

 notable specializations of structure which occur in fishes and serve 

 definite habits is found in the flying fish, which is allied to the Billfish 

 and Half-beak. The elongated and strengthened breast fins of the 

 flying fish, which wh3n folded extend backward almost or quite to the 

 tail, are spread when the fish leaps from the water, supporting it for 

 protracted journeys through the air. Numerous species of flying 

 fi^es occur in warm seas. They are common in the Gulf Stream off our 

 coast but only by accident -straggle inshore. Three kinds have been 



