150 



Japan represents another species than that from Cape, but the differences 

 are too insignificant for making it necessary to designate it as a separate 

 species at present. In any case the two forms must be very closely 

 related. 



Another, younger specimen, from the same locality and the same day, 

 probably also belongs to this species, although it differs in the antero- 

 lateral arms being longer than the postoral ones and in the suboral cavity 

 being indistinct. In this specimen the posterolateral arms have the same 



outward direction as 

 in the type. 



The suggestion made 

 in the work quoted 

 that this larva may 

 belong to some Am- 

 p/iiura-species is with- 

 out real support. It 

 was made on account 

 of the similarity be- 

 tween this larva and 

 Ophiopluteus bimacu- 



latus (Joh. Miill.), 

 which latter was re- 

 ferred to the genus 

 Amphiura on account 

 TT- ^o r, ^ . X , . , , of the fact that the 



Fig. 78. Part of posterolateral rod of Ophiopluteus similis. 290/ ^ , . . , 



young Ophiurid, as 

 shown in the figures of Joh. Muller (V. Abhandl. Taf. V, Fig. 6) has 

 two papillae on each mouth angle, a feature mainly characteristic of Am- 

 phiura. However, as I have shown recently i) that Ophiopluteus mancus is 

 the larva of Amphiura filiformis, the suggestion that 0. himaculaius might 

 belong to an Amphiura becomes improbable. The two papilla of the young 

 Ophiurid are hardly the typical infradental papillae of the Amphiurid type, 

 but more probably tooth papillae situated in the inner part of the mouth! 

 in Amphiura filiformis I have found the infradental papilla to appear 

 only at a much later stage of development. The fact of the occurrence 

 of this larval type both at Cape and Japan is not of sufficient zoogeo- 

 graphical importance for indicating to which species of Ophiurids it belongs 

 Whether it is more nearly related to Ophiopluteus bimaculatus must also 

 remain uncertain for the present. 



^) On the development and the larval forms of some Scandinavian Echinoderms. p. 138. 



Fig. 77. Slceleton of Ophiopluteus similis. ^'Vi, 

 Letters as in fig. 61. 



3v. 



3v_ 



