224 



inighl possibly belong, it seems iiuleed probable tbat it does belong to 

 one of liu' i'ornis occurring in greater depths. The fads that the young 

 starlisli is (i-rathate and liiat it belongs to the Forcijjulata (as jMOved bv 

 its pedicellariae) considerably restrict the nundicr of forms which may 

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

 littoral regions of llie Azores there is not one having normally (1 arms; 

 Aslerids lenuispiiia Lamk. however sometimes has this number of arms, 

 though there are generally seven or eight, in case the " Slellospha'ia' 

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

 the metamorphosing starfish apparently always has this number of arms. 

 The larger number of arms in .1. IcniiispiiKi tiicii imisl l)c due to addilioiial 

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

 improl)ahle, and it is therefore thus far very well |)ossiblc that we have in 

 tiie 'SIcllosplvi'ra' the larva of Aslciids Iciniispiiid. If liiis is not the case, 

 the only other forms known to which it could belong are Aslcrias liirhardi 

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

 Pedicelluslcr sexradialus Peniev and Frei/ella sexradialaPi'vvivv, all of IIumu 

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

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

 Hirhardi, not known with certainty to occur in the .\zorean waters. Thus 

 Pediccllasler sexradialus alone remains, i'he fad that tiiis species has small 

 6ggs ( — as I have had the opportunity to ascertain — ) makes it highly 

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

 celluslcr lypicus, which has large, yolky eggs). 



One might expect that the structure of the pedicellaria? would decide 

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

 not so. the crossed pedicellaria' of the two forms being hardly dilTcrcnl 

 at all. On the other hand the pedicellaria^ of the young starfish, as tiguied 

 by Koehler & Vaney, differ from those of the two siiecies mentioned in 

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

 in both Asl. leiniispina and Pediccllasler sexradialus. This structural difTer- 

 euce might rather bear testimony against the refeiriug of the larva to any 

 of the two said species. It is, however, very well |)ossible that the single 

 series of teeth in the young is an embryonal character. 1 therefore would 

 not deem this structural difference of sufficient iniportaucc to couuler- 

 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 pedicellarite given by Koehler & Vaney). 

 — The occurrence of liie larva ofi' Ireland, which nuiy be regarded almost 



