592 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxiv. 
Head 6 in length; depth at insertion of anal 8i; depth of caudal 
peduncle 4 in head; eye -if; interorbital space 5i; snout 3 jV^ D. 11; 
A. 23; P. 15. Body very elongate, cylindrical anteriorly, compressed 
posteriorly, especially in male specimens, where, in the region of inser- 
tion of anal, the depth is doulile that of the body immediately behind 
the head; the females are more slender; caudal peduncle rather narrow 
and compressed. Head greatl}^ depressed, flat or slightly rounded on 
top, snout spatulate; pointed when seen from the side. Maxillary 
extending to anterior edge of orbit; lower jaw projecting slightly 
bej^ond the upper; teeth in a single row on jaws and palatines, none 
on vomer, those on the premaxillaries enlarged; tongue with a few 
small teeth. Gill-rakers on first arch 3+12, long and slender. Head 
and body naked, a single large, thin scale extending along body at base 
of anal tin in the male, the width of the anterior part of the scale equal 
to distance between the eyes. Dorsal inserted on posterior third of 
body, the highest rays contained two times in head. Adipose fin low, 
the length of its base about equal to depth of caudal peduncle. Caudal 
fin deeply forked, the lower rays slightly longer than the upper, equal 
to length of head. Anal inserted below middle of dorsal, the length of 
its base equal to length of head, the longest rays If in head. Ventrals 
inserted near middle of body, of 7 rays, the outer one longest, 1^ in 
head, its tip somewhat filamentous. Pectorals falcate, 1^ in head. 
Color translucent, except for the eyes, the fish being almost invisible 
in the water; two rows of black dots along the ventral surface. 
The straight alimentary canal, the distinct muscle segmentation, the 
ver}" thin ventral wall of the abdominal cavit}^, and other characters 
suggest a larval stage of development. Specimens about 100 milli- 
meters long are apparently mature, having large eggs in the ovaries. 
This little fish is found at certain seasons in the ba3"S of northern 
Japan in great abundance, probably ascending the streams to spawn. 
It reaches a smaller size than its allies Salanx chinensis of southern 
China and Salanx hyalocranms of Korea and northern China. Our 
many specimens are from Mororan, Aomori, Same, and Tokyo. 
It is reported in Japan that the fish is annual, ascending the streams 
in summer, and all individuals dying in the autumn after the deposition 
of the eggs. This alleged. fact needs verification. 
(/u/cpo's-, small; ocJous", tooth.) 
i6. SALANX ARIAKENSIS Kishinouye, MS. 
"B. 3. D. 13. A. 26. P. 10. V. 7. 
" Length of the head 5^ times contained in the total; head nearly twice as broad 
as high; the diameter of the eye is about one-seventh of the length of the head. 
Teeth subequal. Tongue toothless. Root of the ventral fin in the middle of the 
total length. Dorsal fin opposite to the anal. Adipose fin originates from the base 
of the anal. Body scaleless and nearly colorless, except a few black spots in two 
rows along the ventral median line and the caudal fin, which is light brown. 
