288 ART. 2. — H. MATSUMOTO: 



the second. Two or three arm spines, very minute, peg-like, 

 situated close together in a notch. 



The plates of the disk and arms are minutely tuberculated. 



Colour in alcohol white or pale gray. 



In the smaller one of these specimens, the tentacle pores and 

 scales are entirely absent, so that the second and third ventral 

 arm plates are triangular instead of being pentagonal. 



Lyman's type was much smaller and Kœhlee's specimens 

 much larger than mine. The disk plates are therefore fewest in 

 Lyman's and most numerous in Kœhlee's ; they are moreover 

 separated from one another by narrow grooves in the type, but 

 imbricated in both Kœhlee's specimens and mine. The radial 

 shields are closely in contact in the type, but separated in my 

 specimens, and more so in Kœhlee's. The oral papillœ are most 

 numerous in mine. The two small plates shown in my figure 

 between the oral shield and the largest interbrachial plate do not 

 occur in the type, and are also absent in Kœhlee's specimens and 

 the smaller one of mine. Both in the type and in my specimens, 

 the dorsal surface of the disk and arms is not so prominently 

 tuberculated as is indicated in Kœhlee's fio-ures. 



OjyJiiomusiwin simplex Lyiman. 



OpJtiomusmm simplex : Lyman, BuU. Mus. Comp. Zool., V, 1878, p. 

 115, PI. I, figs. 10 & 11 ; Lyman, Eep. Challenger, V, 1882, p. 93, PL I, 

 figs. 7-9 ; Clark, Bull. U, S. Nat. Mus., LXXV, 1911, p. 109. 



OpMomnsinm sanctum: Ivœhler, Exp. Siboga, XLY, Pt. I, 1904, p. 

 59, PL XT, figs. 7-9. 



Eastern Sea; 71-130 fathoms (Claek). 



Amboyna, Malaysian waters. 



