40 ART. 2. — H. MATSUMOTO : 



« 



ribbons are much more slender than the ovarial ; so that, the 

 dorsal median groove of the arms is much deeper and narrower 

 in the male than in the female. I am inchned to think that, the 

 striking contrast of the ratio of the width to height of the arms 

 in the two specimens is a sexual difference. 



I have one more statement to make about the smaller speci- 

 men, viz. that it is four-armed. Not only the arms but the body 

 generally is quadrimerous throughout, and there are no indications 

 of external injury. The great width of the arms in this specimen 

 might be looked upon as a result of the quadrimerism ; but I 

 think it only explains the great width of the arm bases, and not 

 that of the distal part of the arms within the first bifurcation. 



Key to species of Muryale. 



A — Proximal parts of arms beset with two rows of large stumpy tuber- 

 cles ; some similar tubercles are found also on the radial ribs 



aspera. 



AA — Arms entirely free of stumpy tubercles, but some very small tuber- 

 cles j)i'esent on the radial ribs anopJa. 



Euryale aspera Lamaeck. 



Euryale aspevum : Lamarck, Hist. Nat. Anim. sans Vert., II, 181G, 

 p. 535. 



Aslropliyton aspcriim : Müller & Troschel, Sys. Ast.. 1842, p. 124 ; 

 Ludwig, Zeifschr. wiss. Zool., XXXI, 1878, p. 66. 



Enrijalc asp>era : Lyman, Piop. Challenger, V, 1882, p. 266 ; Studer, 

 Abh. K. Akad. Wiss. Berlin, 1882, p. 53, PI. Y, fig. 10 ; Kœhlee, Bull. Sei. 

 Fr. Belg., XXXI, 1898, p. 114. 



Euryale studer! : LoRiOL, Piev. Suisse Zool., VIII, 1900, p. 8, PI. VIII, 

 fig. 4, PI. IX, fig. 1 ; Kœhler, Exp. Siboga, XLV, Pt. 2, 1905, p. 132 ; 

 Kœhlee, Bull. Sei. Fr. Belg., XLI, 1907, p. 350. 



