278 THE VOYAGE OF H.M.S. CHALLENGER. 



1. The Solaris-growp. 



Ten arms. The two outer radials and the first two brachials respectively united by 

 sj^ygy. 



A. Less than twenty-five cirrus-joints. The basal joints of the lower pinnules 



usually have more or less prominent keels. 



Nine to fifteen cirrus-joints, . . . . . . .1. pectinata, Retz., sp. 



Seventeen to twenty-three cirrus-joints, . . . . .2. Solaris, Lam., sp. 



B. Thirty to thirty-five cirrus-joints. The basal joints of the lower pinnules not 



specially distinguished, ....... brachiolata, Lam., sp. 



Seven other species besides the three contained in the above list have been referred 

 to this group at different times, viz., Actinometra hamata, Herklots, Actinometra 

 imperialis, Midler, Actinometra intermedia, Bell, Actinometra purpurea, Miiller, sp., 

 Actinometra robusta, Liitken, MS., Actinometra rosea, Miiller, sp., and Actinometra 

 strota, P. H. Carpenter, MS. The first four are synonyms of either Actinometra 

 pectinata or Actinometra Solaris, while the only character on which Miiller relied 

 as separating Comatula rosea from Comatula brachiolata was the absence in the 

 latter of a terminal comb on the oral pinnules ; and I have since found this comb to 

 be present in the type specimens, both at Berlin and at Vienna. Alecto purpurea 

 is a small form which was described by Miiller in 1843, before he had himself examined 

 Lamarck's types at Paris, but it afterwards appeared to him to differ from Actinometra 

 Solaris only in showing two radials externally instead of three ; and he thought that the 

 difference might possibly be due to the immaturity of the specimen, which he regarded 

 as probably a young form of Actinometra Solaris. Both the Paris and Vienna 

 specimens of this type have twenty cirrus-joints ; and Miiller described Alecto 

 purpurea as having only twelve, so that it should probably be referred to Actinometra 

 pectinata. 



Comatula (Actinometra ?) hamata was the name given by Herklots ' to a specimen 

 in the Leyden Museum from Cape Bantano, which was figured by Kuhl and van Hasselt, 

 but is not, however, sufficiently distinct from the general type of Actinometra Solaris to 

 justify the establishment of another species. I believe uow that the same may be said 

 of Actinometra imperialis, Miiller, of Liitken's MS. species Actinometra robusta, of the 

 form which I have hitherto called Actinometra strota, and also of Actinometra inter- 

 media, Bell. This may seem to be a somewhat comprehensive statement ; but it is the 

 result of a careful and often-repeated examination of a very large amount of material, 

 including the type specimens at Lund, Paris, Berlin, Vienna, Leyden, Copenhagen, and 

 in the British Museum, besides numerous isolated specimens in other collections. My 



1 Echinodermes peintes d'apres nature par les soins de Kuhl, van Hasselt, et Sal. Miiller, Bijdragen tot de 

 Dierkunde, 1869, Bd. ix. p. 10, pL is. 



