124 BULLETIN : MUSEUM OF COMPAKATIVE ZOOLOGY. 



of more abundant material it will be shown that some of the species here placed 

 as synonyms of 0. gorgonia are really entitled to recognition. 



Ophiarachnella infernalis. 



Ophiarachna infernalis Miiller and Troschel, 1842. Sys. Ast., p. 105. 



Pectinura infernalis Liitken, 1869. Add. Hist. Oph., 3, p. 33. 



Pectinura similis Koehler, 1905. Oph. " Siboga " Litt., p. 6, pi. 1. figs. 4-6. 



Indian Ocean ; near Sumatra ; Philippines ; Queensland ; Torres Strait ; Pelew 

 Islands; Zanzibar; Sorong, New Guinea; Amboina; a dozen " Siboga " stations in 

 the Dutch East Indies. Littoral to 33 fms. 



It is with great hesitation that I disagree with so excellent an authority as M. 

 Koehler concerning the distinctive features of this species, but the 37 specimens 

 in the M. C. Z. collections have convinced me that it is not possible to distinguish 

 the form designated by Koehler (1. c) as 0. similis from the ordinary 0. infernalis. 

 The size, number, and position of the bare plates of the disc and the number of 

 arm-spines show so great diversity in the specimens before me that I find it prac- 

 tically impossible to delimit more than a single species. It is true that none of 

 the specimens studied is a typical 0. similis, but some of them have 11 arm-spines, 

 and others approach that form in the dorsal plates and radial shields. As the " Si- 

 boga" twice took 0. similis and 0. infernalis at the same station, there is evi- 

 dently no geographical or bathymetrical line between the two forms. 



Ophiarachnella angulata. 

 Pectinura angulata Lyman, 1883. Bull. M. C. Z., 10, p. 232, pi. 3, figs. 7-9. 



West Indies, S8-248 fms. ; Bahama Bank. 



Koehler (Oph. " Siboga " Mer Prof., p. 9) speaks of 0. angulata as having 

 " une seule ecaille tentacnlaire " ; this is an unaccountable mistake, for Lyman says 

 distinctly " two tentacle-scales " and the specimens before me show the tentacle- 

 scales to be exactly like those of other species of Ophiarachnella. 



Ophiarachnella paucispina. 



Pectinura paucispina Koehler, 1905. Oph. " Siboga " Litt., p. 4, pi. 1, figs. 13-15. 

 Strait of Makassar, 20 fms. ; off Waigiou, 45 fms. 



Ophiarachnella sphenisci. 

 Pectinura sphenisci Bell, 1894. Proc. Zool. Soc. London, p. 406, pi. 25, figs. 7-9. 



Holothuria Bank, N. W. Australia; N. coast of Celebes; near Amboina; off 

 Aru Islands. Littoral to 25 fms. 



Koehler (Oph. " Siboga " Litt., p. 10) says that Bell's type was from Maccles- 

 field Bank, while Bell himself says it was from Holothuria Bank. Koehler's very 

 natural mistake is due to the misleading title of Bell's paper. 



