REPORT ON THE OPHIUROIDEA. 173 



Ophiocoma papUlosa, Lym., 111. Cat. Mus. Comp. Zool., No. viii., part 2, p. 11, 1875. 

 Lower California ; 22 fathoms. 



Ophiarachna. 

 Ophiarachna, Mull & Tr., Syst. Ast., 1842. 



Disk granulated. Radial shields covered. Teeth, and mouth papillae, and very 

 numerous close-set tooth papillae, arranged in a vertical clump. Spines, usually from four 

 to six ; smooth and solid. One or two tentacle scales. Two genital openings, beginning 

 outside the mouth shield, which has, outside and joining it, a supplementary shield. 



As might be expected, from its external appearance, the skeleton of this genus is 

 much like that of Ophiocoma, except that the peristomial plate is quite large and thick, 

 and composed of three pieces, whereof the two largest form an open angle which is closed 

 by the third. 



Species of Ophiarachna not herein described. 



Ophiarachna incrassata, Mull. & Tr., Syst. Ast., p. 104, 1842 ; Ltk., Addit. ad Hist., 



part 3, p. 33 ; Lym., Bull. Mus. Comp. Zool., vol. iii., part 10, p. 221 ; Ludwig, Anatomie 



der Ophiuren Zeits. fur Wissen. Zoologie, vol. xxxi. p. 241. 



Ophiura incrassata, Lnik., Hist. Anim. sans Vert., vol. ii. p. 542, 1816. 

 Ophiocoma ocellata, V. Mart., Monatsb. Kbnig. Akad. Berlin, p. 345, 1867. 



Great Ocean. 



Ophiarachna affinis, Ltk., Addit. ad Hist., part 3, pp. 34 and 98, 1869 ; Lym., Bull. 

 Mus. Comp. Zool, vol. iii., part 10, p. 221. 

 Fiji Islands. 



Ophiarachna armata, Troschel, Site, niederrhein. Gesell. in Bonn., p. 137, March 

 1879. 



Mauritius. 



Ophiarthrum. 



Ophiarthrum, Pet., Monatsb. Konig. Akad. Berlin, 1851. 



Disk quite naked. Radial shields covered. Teeth, mouth papillae, and very numerous 



close-set tooth papillae, arranged in a vertical clump. Spines usually from four to six ; 



smooth, and solid. One or two tentacle scales. Two genital openings, beginning outside 



the mouth shield. 



This genus is essentially an Opjhiocoma whose skin is but feebly calcified, and the 

 disk is therefore destitute of external granulation and even of scales. In its substance 

 (zool. chall. exp. — part xiv. — 1882.) O 23 



