128 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



Oral shields wider than long ; disc brown and yellowish ; arms 

 annulated- affinis 



Oral shields longer than wide; disc uniform, deep brown; arms 



not annulated mauritiensis 



Radial shields bare; disc brown, more or less variegated with 



yellow ; arm-spines 4-5 . . . . , robillardi 



Ophiarachna incrassata. 



Ophiura incrassata Lamarck, 1816. Anim. sans Vert., 2, p. 542. 

 Ophiarachna incrassata Miiller and Troschel, 1842. Sys. Ast., p. 104. 



Java ; Pelew Islands ; Philippines ; New Britain ; Amboina ; Timor ; half a 

 dozen " Siboga " stations in D. E. I.; "Sea of Bengal ;" Ceylon; Zanzibar; 

 Darros Island ; "intertropical Australia." Littoral to 20 fms. 



A specimen in the M. C. Z. collection measures 56 mm. across the disc and is 

 the largest simple-armed ophiuran of which I can find any record. 



Ophiarachna affinis. 



Ophiarachna affinis Liitken, 1869. Add. Hist. Oph., 3, p. 33. 

 Ophiarachna clavigera Brock, 1888. Zeits. f. w. Zool., 47, p. 47. 



Fiji Islands ; Samoa ; Amboina ; Fernando Veloso, Mozambique. Littoral. 



Both de Loriol (Rev. Suisse de Zool., 1, p. 411) and Koehler (Mem. Soc. Zool. 

 France, 17, p. 70) are agreed that 0. clavigera Brock is a synonym of 0. affinis, 

 and I see no reason to doubt their decision. It does seem doubtful, however, 

 whether the specimen recorded by Koehler (Bull. Sci. France et Belgique, 41, 

 p. 330) from Fernando Veloso, with only 3-4 arm-spines, is really 0. affinis. 

 The locality and the very small number of arm-spines cause one to be 

 suspicious. 



Ophiarachna mauritiensis. 



Ophiarachna mauritiensis de Loriol, 1894. Mem. Soc. Phys. et Hist. Nat. Geneve, 

 32, pt. 1, no. 3, p. 32, pi. 24, figs. 1-le. 



Mauritius. 



Ophiarachna robillardi. 



Ophiarachna robillardi de Loriol, 1894. Mem. Soc. Phys. et Hist. Nat. Geneve, 32, 

 pt. 1, no. 3, p. 31, pi. 23, tigs. 5-5e. 



Mauritius. 



Bathypectinura, gen. nov. 



(Greek $a8vs = deep 4- pectinura, in reference to the characteristic habitat of the 

 group.) 



Disc, excepting radial shields, covered above and below by granules, which 

 more or less fully conceal the underlying layer of scales. Radial shields of moder- 

 ate or small size, bare, but not conspicuous. Oral shields conspicuous, but sup- 

 plementary oral plates rudimentary or wholly wanting. Arm-spines relatively 



