214 



that, even after the recent subdivision of the great genus Ophiura (Matsu- 

 moto, H. L. Clark), these two species are left in the same subdivision, 

 the genus Ophiura s. str., which would mean that a further subdivision of 

 this genus is necessary. In this connection it is important to notice that 

 most probably Ophiura affinis and the mediterranean 0. Gruhei, which has 

 unjustly been made a synonym of the former, have larvae of almost iden- 

 tical structure^). Further the Ophiopluteus fusus, described in the present 

 work, recalls the Ophiura albida-larva to a considerable degree, so that it 

 might well seem that here again we have the larvae of two really related 

 forms. ( — 0. fusus being found at the Azores, one might perhaps think 

 of Ophiura Thoiileti Koehler as its parental form — ). Regarding Ophiura 

 texturata, the larva of which is quite unique among the Ophiurid-larvae 

 hitherto known through its fenestrated posterolateral rods, it is worth 

 pointing out that this species is very peculiar by its series of pores along 

 the ventral midline of the arms, therein differing markedly from the other 

 species of the genus. Upon the whole, I would think it very probable that 

 the genus Ophiura (or Ophioglypha) in its wider sense is a parallel to the 

 Camarodonta within the Echinoids, that is to say, representing the most 

 specialized type, in which the "coarser" characters, if I may use such an 

 expression, have reached such a point of specialization and uniformity that 

 they do not afford a sufficient base for further classification. The generic 

 characters would then have to be looked for among the minor, morpho- 

 logically less important structures, just as in the Camarodonta the char- 

 acters of the pedicellarise and spicules set in, where the morphologically 

 much more important characters of the test structure are failing as a suf- 

 ficient base for classification. This is, of course, only meant as an idea to 

 be tested by further studies. But in any case, it would seem perfectly 

 absurd, in view of the facts here made known regarding the Ophiurid 

 larvae, to draw the opposite conclusion that, since the larvae of forms so 

 closely alike as Ophiura albida, affinis and texturata differ so markedly 

 from one another, the Ophiurid larvae have no classificatory value at all. 

 While it thus seems an established fact that within the Ophiuroid-larvae 

 several very distinct generic types may be discerned, it is, at the present 

 state of our knowledge, impossible to say whether "family "-types also may 

 be distinguished. There is some probability that the family Ophiothrichidae 

 has a distinct larval type of its own, perhaps also the Ophiocomidae 

 have a distinct larval type — but very much more knowledge is required, 

 before we can form a safe judgment of this problem, 



') Coiup. Ihe author's paper ■XoLcs on Lhe developmenl and Ihe larval forms of some 

 Scandinavian Echinoderms", p. 135. 



