86 ^ Ml— H * (?) V >f V =)■ 



third and the anal are short and curved, the length being the same or one third of 

 the free spines ; the ventral spine long, and its length equalling the snout and the 

 pupil ; it has a basal cusp, followed by a soft ray. The lateral armature above 

 the pectorals ; they are of six oblong plates which anteriorly diminish their size ; no 

 keel on the caudal peduncle. The colouration bronwish or bluish dark above, pale 

 below and mottled. The vernacular name is itouo from the striation of the lateral 

 armature giving it the appearance of a skein of thread. 

 B. Pygosteus. 



Many spined stickle-backs. The spines more than nine. The body naked 



or partly mailed. Gill openings confluent with a fold of gill membrane across 



the isthumus. 



1. Body slender with a rather long caudal peduncle ; free spines nine, long and 

 divergent. Pygoste^ts steindacJineri. 



2. Body naked and not slender, with a rather long caudal peduncle ; free spines 

 nine, short and divergent. Pygosteiis brevispinosus, n. sp. 



3. Body thicker ; free spines eleven, short. Pygostciis uiideciinalis. 



Pygostetis steindacJineri, Jordan & Snyder. 



A long spined stickle back with a slender body. The specimens from 

 Rebun, an islet on the north-eastern coast of Hokkaido. They arc compressed 

 \vith a depressed caudal peduncle. 



The largest specimens are 7 cm long. 



D. IX, (VIII rarely) lo-ii (occasionally 9 or 12), A. I, lo-ii (8 or 9), P. 10. 

 Height 4I in the length ; in male the length is a little longer and slender 

 with a pointed snout; depth 61. The diameter of eye equals snout or slightly longer, 

 it is 31^ in head ; the interorbital space | in eye ; tlie maxillaries are far from 

 reaching the anterior margin of eye, but reaching nearly below the nare. The dor- 

 sal spines divergent and without the supporting membrane ; they are folded alter- 

 nately when depressed, and the lengths are all equal; ventral spines long, the length 

 ec^ualling the snout and the pupil of eye, the lateral serrature weak and without 

 cusp ; the length of the pectoral fin equals the snout and eye together. The ventral 

 pubic plates lanceolate, reaching the front margin of the vent. The armature small 

 and continuous to the caudal base, forming a strong keel on the caudal peduncle. 

 The ventral fins opposite each other. The fresh colour is dusky greenish pale 

 above, the cheeks and the chin colourless. The spawning colour of some specimens 

 from Sapporo is very dark and dusky. 



Such Japanese names, concerning the stickle-backs, as Jiariuo or haritoto 



