JORDAN AND THOMPSON: FISHES OBTAINED IN JAPAN IN 1911. Pail 
This species is most closely related to Gnathopogon mayede, from which it 
may be at once differentiated by the longer barbel and the extension, when supine, 
of the anal rays, more than half-way from the last anal ray to the first caudal ray. 
Other differences are the scales enlarged in the middle line of the back, the presence 
of one more series of scales above the lateral line, the slightly shorter distance from 
the tip of the snout to the occiput, the longer ventrals, and deeper caudal peduncle. 
Among the cotypes are both males and females, with ripe gonads. The male is 
distinguished from the females by the presence of a smooth overgrowth on the front 
and sides of the snout. The eggs are small, as in others of the genus, being about 
half a millimeter in diameter. Asthe female, which was taken as the type, is the 
most strongly pigmented of any of the specimens, it is probable that the males are 
not, as a rule, colored more highly than the females. 
Among the specimens recorded by Jordan and Snyder from Lake Biwa as 
Leucogobio mayede there are a number of specimens of this species, all of them very 
small. Nos. 6009a-c Lake Biwa. 
This species is named for Professor Chiyomatsu Ishikawa, of the Imperial 
University of Tokyo, who early studied the fishes of Lake Biwa. 
Key TO JAPANESE SPECIES OF Gnathopogon. 
a. Anus distant but the breadth of one scale from first anal ray; pectoral extending less than two-thirds 
of distance to ventrals; gill-rakers numerous, 4+9 or 10; body-depth 4. 
b. Caudal peduncle deep, 8.5 in body; barbel long, three-fifths of diameter of eye; scales 36 to 38; 
pharyngeal teeth only occasionally and slightly serrate...................-.-. elongatus. 
bb. Caudal peduncle slender, about 10 in body; barbel short, one-fourth of diameter of pupil; scales 
42; pharyngeal teeth constantly and strongly serrate on grinding surface........... jordani. 
aa. Anus distant at least 2.5 scales from first anal ray (two-thirds of eye); pectoral extending more than 
two-thirds distance to ventrals; gill-rakers short and rudimentary, 3 or 4+4, lacking anteriorly. 
c. Depth 4 in body; anus 2.5 scales (two-thirds diameter of eye) distant from first anal ray. 
d. Seales in middle line of back enlarged; rows between lateral line and dorsal 3.5; anal rays 
extending over half-way from base of last to first caudal rays; maxillary not reaching 
beyond orbit, its barbel under nostril; barbel two-thirds of eye............. ishikawe. 
dd. Scales in middle line of back not enlarged; rows between lateral line and dorsal 4.5; anal 
rays not extending half-way to first caudal rays; maxillary reaching beyond orbit; its 
panpeleshort mlessmp halen Upulerer epee er eta tts carina tela uateler che) cielaierelos sini mayede. 
cc. Depth 6 in body-length; anus distant the breadth of 4.5 scales (1.16 times diameter of eye) from 
insertion of anal fin; 5 scales above lateral line; barbel one-half diameter of eye; scales in 
murddlesdineros packw but shehtly enlarges a cje..cicttels oleic wie epencteie = totals) sicls efera) o's) tiers gracilis. 
48. Acheilognathus rhombeus (Temminck «& Schlegel). 
Lake Biwa, at Matsubara, No. 6327 many. 
Capoeta rhombea Schlegel, Fauna Japonica, Poiss., 1846, p. 205, pl. C., fig. 6; near Nagasaki. 
Acheilognathus rhombeus Bleeker, Prodr. Cypr., 1, 1860, p. 255. 
