215 



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

 with those given in the present work, decidedly tend to show that there 

 are distinct "family" types of the larvae, corresponding to the families of 

 the adult. Unfortunately, our knowledge is still very limited, so thai there 

 is only a poor foundation for the conclusions: 1ml the little we know speaks 

 rather clearly. 



Within the Aslropectinida? we know the larva- of four dilTerent species, 

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

 the larva 1 do not develop into a Brachiolaria. By the metamorphosis the 

 whole larval body is absorbed. - - Within the Lnidiidte we know the larva 1 

 of the two species Luidiu Sarsi and ciliaris, which both agree so closely 

 in their characters that it is difficult 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 posterior part of 

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

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

 morphosis is completed. The fact that "Bipinnaria asU'riyrra" 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 support to the conclusion that we have here a 

 distinct larval type, characteristic of the genus Luidia. Whether we may 

 conclude this much that these two larval lypes represent the larva? of the 

 families of the Astropectinida? and Luidikhe, is, of course, doubtful. Bnl, 

 a I leasl, there is nothing to disprove it. 



Within the other families the few facts known of the development of 

 the Asterinida? and the Gymnasteridae hardly form a sufficient base for any 

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

 character of the rudimentary larva- of Asterina i/ibbosa and I'.riyua, com- 

 bined with the fact lhal the larva of Asleriiut pt'clinijt'ni develops into a 

 Brachiolaria, lend to show lhal wilhin Ihis genus (s. lal.) the larva- typic- 

 ally have a Brachiolaria-stage. 



Wilhin the genus Aslcritis the development of I he species A. rubenx 

 and Dulyuris has been studied very completely, and of a third, A. ylacialis. 

 enough is known to stale that ils larva agrees very closely with those of 

 the other two species. It appears lhal we have here a very distinct larval 

 type, characterized through ils long, movable processes, and developing 

 into a Brachiolaria 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, Ortluislcruis Icplulciut, Kiutslcrias 

 Troscheli, seem lo indicate lhal these forms also have a Brachiolaria-stage; 



