CLARK: AUSTRALIAN AND INDO-PACIFIC ECH1NODERMS. 121 



Ophiochasma stellata. 



Ophiarachna stellata Ljungman, 1867. Ofv. Kongl. Vet.-Ak. Forh., 23, p. 305. 



Ophiolepis adspersa Grube, 1868. 45tli Jalires-Bericht d. Schles. Gesell., p. 44. 



Ophiolepis (Ophiochasma) adspersa Grube, I. c, p. 45. 



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



" Ophiochasma (Ophiolepis) adspersum Grube" Lyman, 1882. "Challenger" Oph., 



p. 15. 

 " Ophiarachnella stellata Ljn." Lyman, 1. c. 

 Ophiopinax stellatus Bell, 1884. " Alert " Kept., p. 136, pi. 8, fig. C. 



Singapore ; East Indies ; Philippine Islands ; Queensland ; Torres Straits ; 

 Gulf of Siam. Littoral. 



Ophiarachnella. 



Ljungman, 1872. Ofv. Kongl. Vet.-Ak. Fbrh., 28, p. 640. 



Type, 0. gorgonia (Ophiarachna) Midler and Trosehel, 1842. Sys. Ast., p. 105. 



Unfortunately Ljungman failed to designate any type, his only statement being 

 "Pectinura Ltk. ; Ophiarachna M. Tr. ex parte." But Liitken (1S69, Add. 

 Hist, Oph., 3, p. 33) had definitely restricted Pectinura to P. vestita Forbes, 

 P. stellata Ljungman, and P. gorgonia Muller and Trosehel ; 1 and since P. gorgonia 

 is the only one cf these of which it can be said in any sense " Ophiarachna M. Tr. 

 ex parte," it seems clear that that species must be the type of Ophiarachnella. 

 Lyman evidently considered P. stellata the generic type, for he gives as a 

 synonym of Pectinura stellata, " Ophiarachnella stellata Ljn., Dr. Goes, Oph. 

 Ofv. Kongl. Akad., p. 640, 1871 " (" Challenger " Oph., p. 15). But, if Ljungman 

 had intended P. stellata to be the type-species, he would have written " Ophiar- 

 achna Ljn. ex parte" instead of "Ophiarachna M. Tr. ex parte." As already 

 stated it seems desirable to use this generic name for the majority of those 

 ophiurans which have hitherto been called Pectinura. The well-known species 

 P. gorgonia M. & T. is not only the type, but also fortunately an excellent ex- 

 ample of the group, as the radial shields are of moderate size and very distinct, 

 the tentacle-scales are noticeable for their characteristic form and position, and the 

 arm-spines, though above the average in number, are short and appressed. There 

 appear to be at least fourteen other species which belong in the same genus. 



Key to the Species of Ophiarachnella. 



Radial shields more or less elongate, of moderate or large size 

 (length commonly much more than fa diameter of disc), usually 

 not darker in color than disc ; usually not more than 3 pairs of 

 arm-pores visible. 



1 Lutken's statement concerning P. infernalis and P. septemspinosa of Midler 

 and Trosehel is ambiguous, but it is clear he did not consider them typical of 

 Pectinura. Either, however, might be taken as the type of Ophiarachnella if neces- 

 sary, as they are congeneric with P. gorgonia. 



