The aulhor of llu' ijirsiiil work has lor a long time reahzed that the 

 slii(l\ ol' the hu\;i' would lia\i' an iiiipoilaiil ht'aring also on llu' classi- 

 ticalioii ol' llu' adull I'orms. and il \v;is. indeed, mainly liom this point 

 of view Ihal the invesligalions recorded in this work were undertaken. 



While il is obvious enough Ihal the pelagic larva' nuisl he ol' consider- 

 able importance lor the geographical dislribulion, the question whether 

 they have also a bearing on classilication is, however, not so easily settled. 

 It is. ol couise. uncU'niahlf that tlu'ii- organization and shape is stamped 

 by till' adaptation to llie pelagic lire; l)ul are the laival chin aclers purely 

 secondary adai)lalions, which cannot possibly alTord any clue to the 

 natural aflinities of the adnll forms? The aulhor has gradually become 

 more and more convinced thai this is nol the case, but that they do really 

 have a classilicalory value. Airead\ in Ihe Pari 1 of the "Ingolf" !'>hi- 

 noidea (HH).'i. p. Ill) tlic possibility of linding in the laival forms facts 

 that might be of xalue tor classification was hinted al, the great dif- 

 ference known to exist e. g. between the larva of Spluvrechinus (iranulaiis 

 and those of the /'>/?;/7n.s-species being mentioned as indicating "at all 

 events, tiial very interesting things may be found here." 



The fads hilherlo made known regarding Ihe larval forms of Kchino- 

 derms would seem u|)oii lln' whole to supjiorl the idea thai there is a 

 distinct inlen-elation Indween the laiv;e and the adults, thai the classi- 

 lication of the larvcie corresponds to that of their adull |)arenlal forms. 

 Thus e. g. the Spalangoid larva* have the |)eculiar character in common 

 that there is a long unpaired process from the hindparl of their body, 

 and not a single exception is known to this rule. The larvae of Echinus, 

 Psdiiimcchiniis and l^dnurnliotus all agree in having in their first stage the 

 body considerably elongated beyond the stomach and supported by 

 an elongaled, clubshapi'd body lod, while in Ihe later stage this rod 

 becomes absorbed, so that the body is shortened, being in the same time 

 provided with vibralile epaulelles, while no posterior transverse roti is 

 developed. 11 would thus seem that here we have a distinct larval type 

 peculiai- to the family l^chinida\ The C.lypeastroid larva^ hitherto described 

 (Echinocf/diniis i)iisillus. I'^chiiKiidchnius jxirmd and Mcllild Icsludinala) 

 all agree in the general character of tiic larval shape and the structure of 

 the larval skeleton (the body skeleton foiining a basket structure), so that 

 il has Ihe apj)earance thai there is a (-lypeastroid larval ty|)c' as distinct 

 as the Spalangoid type. Among the Asteroids it seems evident that there 

 is a distinct larval type, Ihe so-called Brachiolaria, peculiar lo the family 

 .\sterida', characterized mainly by its lound lirachiolarian processes, 

 while the type of Bipinnaria asleru/eru (the first Echinoderm larva de.scrib- 

 ed) a|)pears lo be characlerislic of the family l.uidiida'. 



