ELEOTRIDJE 25 



ELEOTRID^E 



In this group are included those gobies with the ventral fins 

 placed very near together but more or less disconnected, and 

 never united to form a single disklike or sucking organ for 

 attaching the fish to objects; the dorsal fins are separate or 

 united only at the base; the eyes are not stalked or unusually 

 prominent ; the body is more or less elongate, cylindrical or com- 

 pressed ; branchiostegals four to six, one or more of them ending 

 in an anterior spine in some genera ; the body may be scaled or 

 naked. An air bladder is present in most of the genera; ven- 

 trals 1-5 in our genera. 



The eleotrids are abundant in East Indian waters, especially 

 in shallow bays and the mouths of rivers. Some of them are 

 exclusively marine reef dwellers, but the largest and economically 

 most important ascend rivers and enter lakes far beyond 

 the influence of the tides. While it is possible that some eleo- 

 trids are exclusively fresh-water, I have no evidence to that effect. 

 I believe that those found in fresh water spend at least part of 

 their lives in salt water, going down to the sea to spawn, no 

 matter how far in the interior they may dwell most of the time. 

 To this statement the genus Hypseleotris is probably an ex- 

 ception. 



In this paper are described eighteen genera of eleotrids, 

 four of them new, and thirty-two species, of which eleven are 

 new. There is little doubt that a more extended search of the 

 coral reefs and the streams of Mindanao and Palawan will re- 

 veal at least a third more species than the number here given. 



Most eleotrids are plainly colored and inconspicuous, but a 

 few species, especially coral-reef inhabitants, are very brilliantly 

 colored. One is our most beautifully colored fresh-water fish. 

 Many of them are able to change their color to a remarkable de- 

 gree, according to the character of the substratum and the 

 amount of light present. Such fishes as Eleotris fusca, Bunaka 

 pinguis, and species of Butis can alter their dorsal color from 

 blackish brown to clay gray or putty color ; in moderately strong 

 light the gray is confined to a broad band running lengthwise 

 on each side of the back from the snout to the tail, but with 

 stronger light the entire back becomes uniformly pale. With 

 other light conditions the whole back and sides may be marked 

 by longitudinal gray and blackish lines. By these means the 



