CLARK: AUSTEALIAX AND INDO-PACIFIC ECHINODERMS. 121 



Ophiochasma stellata. 



Opkiarachna stellata Ljungman, 1867. (jfv. Kongl. Yet.-Ak. Forh., 23, p. 305. 



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



Ophiolepis {Oiihiochasma) adspersa Grube, 1. c, p. 45. 



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



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



p. 15. 

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

 Ophiopinax stellatus Bell, 1884. " Alert " Kept., p. 186, pi. 8, fig. C. 



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

 Gulf of Siam. Littoral. 



Ophiarachnella. 



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



Type, 0. gorgonia (Ophiarachna) Miiller and Troschel, 1842. Sys. Ast., p. 105. 



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

 "Pectinura Ltk. ; Opliiarachua M. Tr. ex parte." But Lutkeu (1S69, Add. 

 Hist. Opli., 3, p. 33) had definitely restricted Pectinura to P. ves/ifa Porbes, 

 P. stellata Ljungman, and P. yo/yo«?« Miiller and Troschel ;i smd since P . fforffonia 

 is the only one of tliese 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 evideutly considered P. stellata the generic type, for he gives as a 

 synonym of Pecti?iura stellata, " Ophiarachnella stellata Ljn., Dr. Goes, Oph. 

 6fv. Kongl. Akad., p. 640, 1871 " (" Challenger " Oph., p. 15). But if Ljungman 

 Lad intended P. stellata to be tlie 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 jjosition, 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 ji^ diameter of disc), usually 



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



arm-pores visible. 



1 Liitken's statement concerning P. infernalis and P. septemspinosa of Miiller 

 and Troschel 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. 



