348 ART. 2. — H. MATSUMOTO : 



Key to Japanese species of Ophiomastix, 



A — Disk closely covered with granules and bearing a number of very 

 short spines ; dorsal arm plates fan-shaped ; colom' dark red in life 



and whitish in alcohol mixta. 



A A — Disk sparsely covered with spines, or with spines and granules, 

 neither being very close-set. 

 a — Disk sparsely covered with both spines and granules ; dorsal arm 



plates hexagonal ; colour black IVdkeni. 



aa — Disk sparsely covered Avith spines only ; dorsal arm plates rhom- 

 boidal ; colour grayish brown, disk spines and arm sxjines finely 

 annulated with white cinnulosa. 



Oxyhioniastix fnixta Lütken. 



Ophiomastix mixta : Lütken, Add. Hist. Oph., Pt. HI, 1869, p. 44 ; 

 Lyman, 111. Cat. Mus. Comp. Zool., YI, 1870, p. 15; Lyman, Rep. Challen- 

 ger, V, 1882. p. 175; Brock, Zeitschr. wiss. Zool., XLVII, 1888, p. 497; 

 LoRiOL, Rev. Suisse Zool, I, 1893, p. 414 ; Kœhler, Exp. Siboga, XLV, 

 Pt. 2, 1905, p. 68, PI. YI, fig. 15, PI. XV, fig. 1 ; Clark, Bull. U. S. Nat. 

 Mus., LXXV, 1911, p. 256, fig. 126. 



Fig. 97. Ophiomastix mixta. x3. a. From above, b. From below, c. Side 

 view of three arm joints near disk. 



