142 



CALIFORNIA ACADEMY OF SCIENCES 



scales, as in P. rcdifmnmn. There is no indication in our specimens of blue streaks on the head, 

 but such may well be present in the young. 



Head 3^ to 3-fV in length; depth if to i|. D. XII, 14; A. II, 12. The lateral line traverses 

 20 scales (19 in one specimen); 26 or 27 scales in a series along the middle of the sides; 9 scales in a 

 series between lateral line and anus, 3 between lateral line and front of dorsal. There are fewer 

 accessory scales on top of head than in P. redifrcEnum. 



The preopercular margin is sharply serrate to or slightly below the angle; the horizontal limb 

 is smooth. Preorbital sharply serrate with slender retrorsely curved spines, which occur as far forward 

 as the angle of the mouth, or slightly beyond that point. 



The preorbital is narrower than in P. rectifmnian, its greatest width, opposite angle of 

 mouth, equaling two-thirds diameter of orbit. 



The soft dorsal and anal fins contain constantly 14 and 12 rays, the last split ray being counted 

 as one. Thirteen specimens have been examined as to this point. P. rcdifrcsnum has constantly one 

 more ray in the dorsal and anal. The soft dorsal and anal fins are pointed in all our specimens, 

 whereas they are bluntly rounded in P. redifrcBnum. The ventrals have the outer ray filamentous, 

 extending beyond the vent, usually exceeding the length of the pectoral tin, and equaling the length 

 of the head. 



The species is abundant among reefs and islands in Panama Bay. A single 

 specimen was secured at Acapulco. 



We take pleasure in naming this species for Dr. Theodore Gill, to whom is 

 due much of our early knowledge of Panama fishes. 



Measurements in Hundredths of Length 'without Caudal. 



Length v\'ithout caudal expressed in mm 



Head 



Depth 



Orbit 



Interorbital 



Preorbital at end of maxillary 



Longest dorsal rays 



Longest anal rays 



Length of pectoral 



Length of ventral 



Upper lobe of caudal 



Height of caudal peduncle 



Scales along middle of body 



83 



34 

 54 

 10 

 10 

 6 

 28 



27 

 30 

 32 



31 

 16 

 26 



264. Pomacentrus flavilatus Gill. 

 Not seen by us; recorded by Boulenger (1899, p. 3) from the Gulf of Panama. 



