554 NEW FISHES FROM PACIFIC COAST GILBERT. 



This species seems todifferfrom Upe7ieus Jiavolineatus, from the Indian 

 Ocean and Chinese Seas, in its lower dorsal tin and smaller scales, but 

 I have had no opportunity to make a direct comparison. 



18. Poniacentrus leucorus sp. uov. 



Closely allied to Po7nacentrus fuscus, but adults differing io the color, 

 and in the length of the second anal spine. 



Head aud sides brown, darker on the upper half of body. No blue 

 spots or lines, aud no yellow. Caudal peduncle brown like rest of body. 

 All the fins jet-black, the pectorals abruptly margined behind with pure 

 white. 



Posterior margin of preopercle and lower edge of suborbital ring- 

 serrulate. Second anal spine very strong; measured from base of 

 sheath much higher than any of the dorsal spines, and as high as high- 

 est soft anal ray, its length contained IJ times in head. Margin of 

 anal rather bluntly rounded ; the soft dorsal pointed, but not much 

 produced, the longest ray IJ in head. Caudal lunate, the lobes very 

 bluntly rounded, the upper longer than the lower. Ventrals with the 

 outer ray produced, reaching past vent. Pectorals broad, rounded, 1^ 

 in head. 



Lateral line with 20 pores; 7 to 9 cross-rows of scales behind its 

 end. 



Interorbital region transversely convex. Anterior profile arched, a 

 slight depression usually to be recognized on nape and on snout. 



Head 3^ in length; depth 2. D. XII, 16; A. II, 13. 



Numerous specimens, 4^ to 5J inches long, were taken at Socorro 

 Island, one of the Revillagigedo Group, off the coast of Mexico. 



19. Gobius microdon sp. nov. 



Allied to Gobiiis sagittula, but much less elongate, with plain colora- 

 ation, aud with minute teeth, those iu the upper jaw in a single series. 

 The species belongs apparently to the section called by Bieeker Oxyii- 

 richthysy but differs from the typical species iu the much less elongate 

 form aud the horizontal mouth. 



Head and body compressed, ev^ery where deeper than wide. Mouth 

 at lower profile of snout, nearly horizontal, the lower jaw extremely 

 weak, broadly rounded anteriorly. Maxillary reaching vertical from 

 hinder margin of pupil, nearly half length of head. 



Teeth minute, scarcely [)erceptible without the use of a lens, those in 

 upper jaw in a single series. Mandible with a close set outer series 

 of teeth, separated by an interval from an inner narrow band of still 

 smaller teeth. 



Interorbital space narrow, less than diameter of piiiul. Isthmus 

 wide, the gill-slits extending little below base of pectorals. 



Scah'S minute and cycloid anteriorly and on belly, becoming larger 

 posteriorly ; ou sides they are everywhere ctenoid behiiul the middle of 



