164 



AKT, 2.— H. MATSUMOTO 



almost exactly like 0. 

 brachyactis, so far as the 

 disk is concerned ; others 

 again have very short 

 and stout arm spines 

 like those of the typical 

 hrachyadis, while the 

 supplementary plates on 

 the sides of the dorsal 

 arm plates are like those 

 of the typical japonica. 

 In the neighbourhood of 

 jNIisaki, the northern 

 japonica and the southern 

 brachyactis occur side by 

 side, and it is very 

 possible that natural 

 hybridisation may occur. 

 Both these species are 

 found clinging to gorge - 



naceans and hexactinellids, and are very often found together on 



the same piece of those animals. 



Fig. 42. OxMoplioUs hrachyadis. x 8. a. From above. 

 h. From below, c. Arm si^ines of one side of an arm 

 joint near disk. d. Arm spines of one side of an arm 

 joint near the extremity. 



Revision of the genera of A^nphiurlnœ, 



The forms which I now bring together under the Amphiurinœ, 

 have hitherto been referred to several genera chiefly on the ground 

 of the character of the disk coverings, such as the presence or 

 absence of scales, complete or localised squamation, the presence 

 or absence of disk spines, &c. But I believe that, such a classi- 



