Clarke. — On the Mangrove Fish. 99 



are simple, but short and very feeble. Ventral fin strong. 

 Upper axillae of pectorals provided with small, short, flat 

 appendage. 



Double row of broad, imbricate, tricuspid teeth along the 

 edges of the upper and lower mandibles, behind which is a 

 " trenched " toothless groove or space, and then the jaws are 

 armed with short, small, flattened teeth in broad band, with 

 points in three very fine cusps but little developed. The 

 anterior edges of palatines, though not armed with distinct 

 teeth, are developed into a certain amount of prominence and 

 density, giving the approximation of a toothed edge. No 

 canines, no teeth on vomer. Tongue very short, broad, and 

 soft, and palatal curtain very pronounced. 



Diameter of eye is contained nearly six times in length 

 of head, also two and a half times in distance from posterior 

 margin of preoperculum to extreme angle of gill-cover. The 

 horizontal limb of preoperculum nearly same length as vertical, 

 and they form almost a rectangle. Sub- and inter-opercula 

 narrow. Projections of the principal frontal bones over the 

 eyes are well padded with flesh, which, with a prominence of 

 the bones below the eyes, causes a groove or depression run- 

 ning from the eye towards and under the nostrils. The cheeks 

 and opercula are flattened. 



The ninth and fifteenth rays of the spinous portion of 

 dorsal are the highest, and length of either is contained exactly 

 five times in the length of base of dorsal, or twice in basal 

 length of anal. The rays gradually increase to this ninth ray, 

 then decrease to the twelfth, then again increase to the last 

 spine, which equals length of ninth. The first three rays of 

 soft part of dorsal equal the length of the ninth or fifteenth 

 rays of spinous. Extreme height of anal fin is much greater 

 than dorsal, and slightly exceeds distance from posterior 

 margin of orbit to extreme angle of gill-opening, or equals ver- 

 tical depth of body under end of dorsal. 



The height of pectorals is contained exactly three times in 

 length of base of dorsal. The distance from snout to orbit 

 is twice the diameter of eye (not orbit). The average breadth 

 of larger scales is about one and three-quarter times the dia- 

 meter of orbit. Top of head rounded between eyes and over 

 nose. Distance between orbits about two and a quarter times 

 diameter of orbit. Distance from anterior margin of orbit 

 to tip of snout is a little more than one and three-quarter 

 times the diameter of orbit. Distance from orbit to angle of 

 jaws slightly exceeds one and a quarter times the diameter of 

 orbit. Distance from upper angle of preoperculum to orbit 

 equals diameter of orbit ; from lower angle equals two dia- 

 meters. Diameter of orbit contained three and one-fifth times 

 in distance from anterior edge of orbit to extreme free angle 



