248 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. XXXII. 



Head 3| in length; depth 2|; eye 3i in head; D. X, 9; A. Ill, 7; 

 scales 5i-42-y. 



Body deeper and more angidutcd than in Xystamia crtjthfouj'mii,' 

 groove of premaxillary .short, obtuse behind; silvery part of maxillary 

 about half longer than deep; snout not projecting; outline of lower 

 jaw slightly concave; longest dorsal spine If in head; longest anal 

 spine 2| ; pectoral as long as head. 



Color silvery, darker above, with faint darker streaks along the 

 rows of scales; tip of dorsal blackish; axil of pectoral dusky; ventrals 

 not tipped with black ; ventrals and membranes of anal spines yellow 

 in life; caudal greenish. 



Fig. 2.— Gekkeomorpha japonica. 



Of this species we have examined three specimens, two from Naha 

 in the Riu Kiu Islands, presented l)v the Imperial University. The 

 other was taken by Messrs. Jordan and Snj^der at Wakanoura. The 

 species may be known at once by the very silvery coloration, by the 

 rather deep body and b}^ the character, called generic, of the ten dorsal 

 spines. 



SUMMARY. 



Family Gerrid^. 



1. Xystcema Jordan and Everniann, 1895. 



1. erijtJirourum (Bloch) 1790; Wakanonra, Oita, Nagasaki. 



2. Gerreomorplia Alleyne and Macleay, 187B. 



2. japonica (Bleeker) 1857; Wakanoura, Naha (Riu Kiu Islands). 



