211 



formation that has been jJiveii Iuti' of its larva is sufficieiil to show that 

 it dilTcrs vfiy inarkt'dly from tiu' true Slronf/i/lorcnlroliis-hwym in its body 

 skeleton in the Hrsl sta^e formin.i^ a baskel-slrnttnre; there is then very 

 good reason to expert that also in its second larval stage it will prove to 

 agree with the Toxopneustid larval type. A I least the facts known are 

 decidedly not in favour of (11 ark's views. 



l^egarding the genera referred by Clark to the family lu-hinometridai 

 there can be no donbl that they really form a natural group, Parnsalenia 

 alone being doubtful. It must then be claimed that the larvae of these 

 forms should be in coidormily wKli one another in their essential features. 

 It is a |Mty thai we do uol know much aboul these larva?, only one species, 

 luhinoinelm luciinlrr, having been reared to its full larval shape and through 

 metamorphosis. I5u( it is known that the larva- of Erhinomcha obloiif/a and 

 (jjloboicntrolus (drains agree with the Ech. lucunlciAaiya in the very char- 

 acteristic feature of the recurrent rod being double, and it is highly prob- 

 able that the same character applies to the larva* of Echinomelra Malhsei 

 and Helerocenlrotus manulldlus. Thus the facts hitherto known regarding 

 the larvae of the Kchinometridai agree very well with the results derived 

 from the study of the adult forms as to their natural aflinilies. 



Summaiizing now the preceding discussion it must be stated that the 

 s t u d }• of the 1 a r V a^ most decidedly lends s u j) p o r t to the author's 

 views as to t he classi f ica t ion of the Camaroflon la , a u d t luis also 

 gives proof of the correctness of ascribing com pa rati vely great 

 importance to the minoi- microscopical characters of pedicel- 

 laria> and spicules in the classification of this group. The classi- 

 ficatory results reached on using these characters, coml)ined with the 

 characters of the test, have been splendidly confirmed through the study 

 of the larva^. Disregarding these characters, Clark was lecl e. g. to such 

 an absurdity as to include Spluerechinus (jiannUuis in the genus SlroiKjiilo- 

 (■cnlroliis, otherwise so naturally circumscribed tiiiongh tiu' peculiar char- 

 acter of its globiferous pedicellaria'. There is no reason to enter here on 

 a discussion of the objections raised especially by Clark against using 

 these microsco])ical characters in classification, as it may now be regarded 

 as an established fact tlial they aie ically of eminenl classilicatoiy value. 

 Thereby I do not mean to maintain that my classification was correct in 

 all details. Tiius e.g. the position assigned by me to the genus .SV/o/ii/y/o- 

 vcnlrolus, mainly on account of the structure of its globiferous pedicel- 

 laria', as being probably related to the Toxoijueustida", was evidently in- 

 correct. The study of the larva^ shows that it is most likely to be an offshoot 

 from the Echinida^ s. str. Upon the w'hole I would emphasi/.e tiiat tlie true 

 position especially of the forms belonging to the Camarodonla, (excepting 



