86 



ART. 2. — H. MATÖUMOTO 



shown in the foregoing key, there are two specific groups in tliis 

 genus, each represented by a Malaysian species. The Arabian 

 species, A. rigens^ is nearly allied to the Malaysian A. vecors, and 

 the Japanese type, A. echinaceus, to the Malaysian A. hellator. 



Astrothamnus echinaceus Matsumoto. 



AstrotJiamtins echinaceus ; Matsumoto, Proc. Acad. Nat. Sei. Philadel- 

 phia. 1915, x>. 55. 



Diameter of disk 22 mm. Length of arms 140 mm. Width 

 of arms at base 4 mm. 



Disk distinctly five-lobed, with five interradial furrows, each 

 lobe being again divided into two secondary lobes by the radial 

 furrow. Radial ribs very prominent, large, occupying almost the 

 whole dorsal surface of disk, leaving between them only ten . narrow 



furrows radiating from the 

 centi'e ; closely covered with 

 rather large stumpy tubercles 

 with thorny crowns, between 

 which lie thick, irregularly 

 polygonal plates. Inter- 

 brachial ventral surfaces 

 strongly concave, closely 

 covered with stumpy tuber- 

 cles terminating with one 

 or a few thorny points. 

 Genital slits rather large, 

 more or less parallel. Mad- 

 reporic shield distinct, small» 



Fig. 2S. Astrothamnus echhmcem. x2^. a. irrCgular in OUtHnC. The 



From above, b. From below, c. Side view of 



three arm joints near disk. . area inside the iuterbrachial 



