224 



might possibly belong, it seems indeed probable that it does belong to 

 one of the forms occurring in greater depths. The facts that the young 

 starfish is 6-radiate and that it belongs to the Forcipulata (as proved by 

 its pedicellarise) considerably restrict the number of forms which may 

 come into consideration. Among the starfishes known to occur in the 

 httoral regions of the Azores there is not one having normally 6 arms; 

 Asterias tenuispina Lamk. however sometimes has this number of arms, 

 though there are generally seven or eight. In case the " Stellosphaera" 

 should belong to this species, it must evidently start with six arms, since 

 the metamorphosing starfish apparently always has this number of arms. 

 The larger number of arms in A. tenuispina then must be due to additional 

 arms formed by regeneration after selfdivision. This is by no means 

 improbable, and it is therefore thus far very well possible that we have in 

 the "Stellosphaera" the larva of Asterias tenuispina. If this is not the case, 

 the only other forms known to which it could belong are Asterias Richardi 

 Perr. (not recorded from the Azores, but not unlikely to occur there), 

 Pedicellaster sexradiatus Perrier and Freyella sexradiata Perrier, all of them 

 deep-water forms. As the larva was found in considerable numbers it is 

 very unhkely that it belongs to the rare Freyella sexradiata or to Asterias 

 Richardi, not known with certainty to occur in the Azorean waters. Thus 

 Pedicellaster sexradiatus alone remains. The fact that this species has small 

 eggs ( — as I have had the opportunity to ascertain — ) makes it highly 

 probable that it has a typical pelagic larva (in contradistinction to Pedi- 

 cellaster typicus, which has large, yolky eggs). 



One might expect that the structure of the pedicellarise would decide 

 the question to which of these species the larva belongs. This is, however, 

 not so, the crossed pedicellarise of the two forms being hardly different 

 at all. On the other hand the pedicellarise of the young starfish, as figured 

 byKoehler&Vaney, differ from those of the two species mentioned in 

 having only one series of teeth along the edge, while there are two series 

 in both Ast. tenuispina and Pedicellaster sexradiatus. This structural differ- 

 ence might rather bear testimony against the referring of the larva to any 

 of the two said species. It is, however, very well possible that the single 

 series of teeth in the young is an embryonal character. I therefore would 

 not deem this structural difference of sufficient importance to counter- 

 balance the fact that no other starfish, which might come into considera- 

 tion as its parental form, is known from the -locality where the larva occurs. 

 (The specimens of the larva examined by me all had their calcareous 

 structures dissolved, so that I have been unable to ascertain myself the 

 correctness of the figures of the pedicellariae given by Koehler & Vaney). 

 — The occurrence of the larva off Ireland, which may be regarded almost 



