215 



Within the Asteroid-larvae tiu- facts previously made known, together 

 witli those given in the present work, decidedly lend lo show that there 

 are distinct "t'anuly" types of tlie larvae, corres|)onding lo the fanulies of 

 the acUdt. Infortunately, our knowledge is still very limited, so that there 

 is only a poor foundation foi tlu' conclusions; but the little we know speaks 

 rather clearly. 



Within the Astropectinida> we know the larvse of four dKYerent species, 

 all agreeing in their main features; the processes are very siiort, rigid, and 

 the larva- do not develop into a Hrachiolaria. By the metamorphosis the 

 whole larval hody is absorbed. — Witiiin the LuidiidcC we know the larvae 

 of liie two s|)ecies Liiidia S(trsi and ciliaris, which both agree so closely 

 in their characters tlial it is diflicult to distinguish them. They are char- 

 acterized by the great elongation of the anterior part of the body which 

 apparently forms an active swimming organ; all the paired arms, which 

 are long and movable, are situated close together in the jjosterior part of 

 the body. There is no Brachiolaria-stage, and the larval body is not ab- 

 sorbed by the metamorphosis but apparently simply cast olT, when meta- 

 morphosis is completed. The fad that "Bipinnaria asterigera" is re- 

 corded from the Celebes-Sea (in the "Summary of Results" of the "Chal- 

 lenger", p. 836) indicates that at least one more species of Luidia^ has a 

 similar larva, which lends supj)ort to the conclusion that we have here a 

 distinct larval type, chai-acteristic of the genus Liiidia. Whether we may 

 conclude this much that these two larval types represent the larva' of the 

 families of the Astropectinida and Luidiiche, is, of course, doubtful. l'>ul. 

 at least, there is nothing to disprove it. 



Within the other families the few facts known of I hi' develo])ment of 

 the .Vsterinida and the (iymnasterida hardly form a suflicient base foi- any 

 conclusion as to the characters of their larva\ I would only say that the 

 chaiacter of the ludimeniary larva of Aslcriiui (/ibbosd and cxiniKi. com- 

 bined with the fact that the larva of Aslciinu pvcHni/cni develops into a 

 Hrachiolaria, tend lo show that within this ijenus (s. lal.) the larvae typic- 

 ally have a iSrachiolaria-stage. 



Within the genus Aslcrias the de\elopmenl of the species .1. lulwns 

 and vulgaris has been studied very completely, and of a Ihird, A. glacialis, 

 enough is known to stale that its laiva agrees very closely with those of 

 the other two species. It appears thai we have here a very dislinct larval 

 ly])e, characterized through its long, movable processes, and developing 

 into a Hrachiolaria with round arms, crowned by a circle of papilla. On 

 metamorphosis the larval body is completely absorbed. The characters of 

 the young larva of some other forms, OrUiasleiias leplolenit, Euasterias 

 Trosdieli, seem to indicati' that tluse formsalso have a Brachiolaria-stage; 



