B ^ CO b ^ t7 9 



^ ift ^ .-t ^r 



STICKLE-BACKS OF JAPAN 



K. Otaki. 



The materials at hand are represented from Sapporo and its \icinitit>' in the 

 island of Hokkaido, from Gifu, Mino Province, and Tamagawa near Tokj'o. Of 

 these specimens the variations of a species in its form, lateral armature, and coloura- 

 tion in the case of Gasterosteus cataphracfiis, are considered to be due to the 

 differences of seasons and changes of environment. Xow that it is impossible, after 

 careful examination, to satisfactorily separate the varied examples in the lateral 

 armature, which is in some full}-, in some, partly mailed, this family of Japan falls 

 into tvvo genera and four species with a new one. 



A. Gasterosteus Togeuo). 



Three spined stickle-back. The free spines three, the tliird spine preceding 

 the dorsal fin ; gill openings restricted and united mesially to the isthmus ; sides of 

 the body partly mailed. 



Gasterosteus cataphractus. Pall. 



A small stickle-back, the size of which exceeds no more than 5^ cm. The 

 distribution ranges extensively throughout Japan. 



D. II — ^. A. I. 7-9(10). P. I. I. 

 10-12 ^ ' 



Body fusiform, slightl}- compressed ; caudal peduncle not compressed. Head 

 rather small and pointed, still smaller in female ; mouth oblique, maxillaries hardly 

 reach the eye. The ventral pubic plates lanceolate, its greatest width if in its 

 length which equals the distance from the tip of snout to the post margin of pupil; the 

 upper shoulder processes reach further beyond the upper base of the pectoral fin. 

 The free spines laterally' separated, long and stoutish, length equalling the snout. 

 They are supported by membrane, but each is not continuous to the other ; the 



[Tran?. S,in. Nat. Hist. Soc VoJ. II , 1937.] 



