223 



the younger. Accordingly the remarkable absorption of the plates and 

 spines, supposed by the authors to take place during the progress of 

 development, does not take place at all, the facts being quite the inverse. 

 The peculiar stage represented in fig. 1 of Koehler's work, showing 

 what appears like two filaments at the "mouth" is only a later stage of 

 development, where the Brachiolarian arms have been almost absorbed, 

 the other arms completely so. 



In 1915 Gemmill^) described a new Asteroid-larva, Brachiolaria hiber- 

 nica, characterized by the point of the Brachiolarian arms being wholly 

 covered with small papillae, and through the presence of a. row of small 

 papillae on each side of the sucking disk, which latter is transversely elong- 

 ated. The single specimen observed (taken in the Atlantic, 50 miles to the 

 W. of Ireland, in a vertical haul from 2165 meters) was in an advanced 

 stage of metamorphosis, the larval arms being reduced to short cylindrical 

 prominences, but Gemmill thinks it very probable that in its younger 

 stages it has the shape of a typical Brachiolaria larva. The characters of 

 this larva exactly agree with those of Stellosphssra mirabilis pointed out 

 here, and the figures of the larva given by Gemmill also recall the Stel- 

 losphsera to such a degree that I cannot doubt that it is really the same 

 larva. It is true that Gemmill does not say anything about its being 

 six-rayed, as is Stellophssra. But his Fig. 1 shows, besides the five young 

 arms, a sixth prominence, which is indicated in the explanation of the 

 figure only as a "prominence of soft tissues in the aboral notch." I can 

 hardly doubt that this is really the beginning 6th arm. (The skeleton, 

 which would have settled the question, was, unfortunately, dissolved). 



Thus, I would think, the " Stellophsera mirabilis" has been definitely 

 deprived of its remarkableness and been reduced to a, probably, quite 

 ordinary Brachiolaria in an advanced stage of metamorphosis. — The 

 suggestion of Koehler & Vaney that it belongs to a deep-sea Asteroid 

 was apparently for a great part due to its supposed fundamental difference 

 from the typical pelagic larvae of httoral Asteroids. The larvae were taken 

 in vertical hauls with open nets, from 3000 m. to the surface; there is thus 

 — asKoehler&Vaneyof course admit — no certainty about the depth 

 in which these larvae were taken. As also other larvae, belonging undoubted- 

 ly to littoral Echinoderms, have been observed far away from the coasts 

 (see below, the chapter on the geographical distribution of the larvae), there 

 seems thus far to be no special reason for regarding the " Stellophaera" as 

 the larva of a deep-sea Asteroid. Still it is possible that it was really taken 

 in greater depths, and if we look up the forms of Starfishes to which it 



1) James F. Gemmill. On a new brachiate Asteroid larva and on the advanced Bipin- 

 naria of Luidia ciliaris (Philippi) Gray. Proc. R. Phys. Soc. Edinburgh. XIX. p. 191. 



