181 



young specimens generally only the ovary at the outer corner oi' the bursal 

 slit is found to contain a young, and mostly of the same size in all the 

 radii. A very large specimen, 39 mm diameter of disk, was found to have 

 all the young, except two of them, hberated. The ovarial sacs were con- 

 tracted as described above. In the same time new ovaries, containing 

 young developmental stages, had been formed: so far as could be ascer- 

 tained these new gonads were formed within the old ovarial sacs. 

 In this specimen in two of the radii testes had been formed in the former 

 female gonad on the corner, even two testes in each. Otherwise the testes 

 were in the normal position and in the usual number of three. Another 

 specimen of 37 mm diameter of disk was quite empty; bul here no embryos 

 were found in the ovaries; the gonads were evidently abortive and the 

 specimen quite senile. It was probably such specimens that were taken 

 by Studer to be male specimens. 



Generally only one young is found in each ovarial sac. In the said large 

 specimen, however, there were in several cases two embryos in the same 

 ovary, mostly in exactly the same stage of development. One ovary was 

 found to contain three embryos in different stages and another even six 

 embryos, in two different stages of development. 



The embryonal development proves to be of exceptional interest. Clea- 

 vage stages were not observed, but it cannot be doubted that it is total 

 as in Aniph. sijiutmata; this may be safely concluded from the fact that 

 a regular blastula is formed. The embryo develops into a compara- 

 tively well formed larva, with a distinct vibratile band and a 

 rudimentary larval skeleton (PI. XXXll, Figs. 1 — 6). The vibratile 

 band remains in a primitive condition, corresponding, in fact, exactly to 

 the diagrammatic figure of the ideal type of an Ophiurid larva represented 

 in ,Joh. Miiller's classical memoir "Uber den allgemeinen Plan in der 

 Entwickelung der Echinodermen" (Taf. 11, Fig. II. 2^)). No larval arms 

 are developed, and the larva thus retains a shape like a young Auricularia; 

 the rudimentary larval skeleton, however, shows it to be a rudimentary 

 Ophiopluteus. Nothing can be said about the typical character of this 

 larval skeleton, it being altogether too rudimentary to be relied upon in 

 this regard, and no conclusions can be drawn as to its relation to other, 

 free Ophiurid larva'. It is almost always seen to consist of two main parts, 

 as in typical Ophiurid larva', but I never saw an embryo with both parts 

 equally developed. 



The posterior end of the larval body is produced into a tip, bearing a 

 rather large tuft of cilia, as it is found, e. g. in the larva of Ophiuva albida 

 and in several other Ophiurid larvae. Mostly the larvae are quite regularly 



') Abh. d. Berliner Akad. 1853. 



