DEC. 28, 1916. FISHES OF PANAMA MEEK AND HILDEBRAND. 349 



Family XL Gobiidae. 



Body oblong or elongate; teeth various, usually small; premaxillaries 

 protractile; gill-openings usually rather small, the membranes attached 

 to the isthmus; opercle unarmed; preopercle unarmed or with a short 

 spine; orbital margin not free, continuous with skin of head; lateral line 

 wanting; scales present or wanting; dorsal fins 2, separate or connected, 

 the first composed of 2 to 8 slender spines; the second dorsal preceded 

 by a single weak spine; margin of caudal fin convex; anal usually similar 

 to second dorsal; ventral fins close together, separate or united, when 

 united forming a sucking disc, consisting of I, 5 or rarely of I, 4 rays, in- 

 serted under base of pectorals; pectoral fins with a broad sub vertical base. 



Most of the representatives of this family are marine, but some of 

 them enter fresh water and rivers. Only the latter of the Panama 

 species are discussed in the present paper. 



KEY TO THE GENERA. 



a. Ventral fins separate. 



b. Vomer with villiform teeth; gill-openings extending forward to 

 below eyes. Philypnus, p. 350. 



bb. Vomerine teeth wanting; gill-openings not extending forward to 

 below eyes. 



c. Head very broad; eyes lateral; jaws anteriorly of equal length; 

 teeth compressed at apices; gill-rakers numerous, well developed, 

 in 2 series on each arch. Intestinal canal long; species herbi- 

 verous. Dormitator, p. 353. 



cc. Head narrower; eyes lateral or not; lower jaw more or less pro- 

 jecting; teeth all pointed; gill-rakers few, poorly developed. 

 Intestinal canal short; species carniverous. 



d. Preopercle with a small, sharp, concealed spine at its lower poste- 

 rior angle. Eleotris, p. 356. 



dd. Preopercle unarmed. 



e. Scales very small, 100 or more in a lateral series. 



Guavina, p. 360. 

 ee. Scales larger, usually fewer than 40 in a lateral series. 



f. Dentary bones broad, expanded, meeting under posterior angle 

 of mouth, leaving an oval-shaped, naked patch at chin. 



Leptophilypnus gen. nov., p. 361. 



ff . Dentary bones narrow, not nearly meeting under posterior angle 

 of mouth. 



g. Head broad depressed; eyes superior; head and chest naked. 



Microeleotris gen. nov., p. 362. 



