GILBERT AND ST ARKS — FISHES OP PANAMA BAY 



177 



The body is rather elongate, the mouth large, oblique, the maxillary reaching slightly beyond 

 the vertical from the posterior margin of the orbit. The interorbital space is very narrow and shal- 

 lovvly grooved, its width but half the diameter of the pupil. The gill-opening is produced below the 

 level of the pectoral base. There are no fleshy appendages on the inner edge of the shoulder girdle. 



The teeth are in a double row in each jaw, those of the outer series enlarged to form 

 slender curved canines, as in other species of Microgobius. The outer series is confined to the anterior 

 portion of each jaw, the inner series extending laterally beyond them. In the mandible, these lateral 

 teeth are somewhat enlarged, replacing those of the outer series, which they do not equal in size. 



The spines of the dorsal fin are all very slender and flexible, all but the first and seventh 

 produced, but connected by membrane to their tips, the tip of the produced lobe reaching middle of 

 soft dorsal when depressed. Soft dorsal and anal of equal extent, high, the last rays slightly over- 

 lapping the caudal. Pectorals and ventrals reach the same vertical, which is slightly behind the origin 

 of the anal fin. The caudal fin is lanceolate, the middle rays produced, their length equaling the 

 distance between the tip of the snout and the base of the middle pectoral rays. 



The scales are large, all but the anterior ones regularly arranged and strongly ctenoid. Ante- 

 riorly, in the post-pectoral region, the scales become reduced in size, cycloid, and less regularly 

 arranged. As nearly as they can be enumerated, there are 44 or 45 in a longitudinal series. The 

 head and nape, a narrow strip along spinous dorsal, and the breast and belly are naked. 



There were no bright colors in life, while in related species (except gulosus) there are blue, 

 green and red. In spirits, the head and body are light grayish olive, with a soiled appearance due 

 to minute punctulations and the faintly darker margins of the scales. The snout, and the marginal 

 portions of the vertical fins, are more distinctly dusky. The sides are crossed by a number of 

 extremely narrow dark lines, 4 or 5 of which can be counted on that part of sides corresponding to 

 anterior halves of dorsal and anal. A more distinct narrow bar descends from the front of the spinous 

 dorsal. Pectorals and ventrals colorless. 



Measurements in Hundredths of Letigth without Caudal. 



Total length in mm 



Length to base of caudal in mm 



Head 



Depth 



Depth of caudal peduncle 



Maxillary 



Eye 



Interorbital width 



Snout to first dorsal spine 



Base of first dorsal 



Base of second dorsal 



Snout to origin of anal 



Base of anal 



Length of caudal 



Length of pectoral 



Length of ventral 



Longest dorsal spine 



39 

 29 

 29 

 21 

 8 



i7i 



8 



2 

 35 

 17 

 38 

 54 

 37 

 33 

 23 

 25 

 39 



