207 



The two classifications are evidently irreconcilable. It is clear that we 

 know perfectly well all the characters which are at all available as a base 

 for the classification. The internal anatomy is so uniform within the whole 

 group that there is no hope of finding therein any characters of value for 

 the classification. Only the structural characters of the test and the organs 

 attached to it, viz. the spines, tubefeet, pedicellariae, and the spicules found 

 in the skin of these organs are available. (The sphaeridiae do not afford 

 characters of classificatory value). The divergences in the two main views 

 on the true relationship of these forms then depend on subjective appre- 

 hension, and further discussion will hardly alter the views on any side 1 ). 

 Only new arguments may be expected to settle the problem and give us 

 a clue as to which of the views regarding the interrelation between the 

 forms within this uniform group comes nearest the truth. Such an argu- 

 ment I have expected to find in the study of their larval forms. The present 

 researches have added so considerably to our knowledge of these larval 

 forms that it is possible to form a reasonable judgment, whether that ex- 

 pectation is justified or not. 



One of the families within the Camarodonta is unquestionably a quite 

 natural group; viz. the Temnopleuridae, or rather the subfamily Temno- 

 pleurinse, the other subfamily, the Teinnechininae or Trigonocidarinae being 

 less distinctly circumscribed. If the larvae are of real value to classifica- 

 tion it must be a just claim that the larvae of the Temnopleurinae should 

 form a corresponding natural group. While hitherto not a single Temno- 

 pleurid-larva was known, we now know, more or less completely, the larvae 

 of Temnopleunis toreumaticus, Temnotrema sculpta and Mespilia ylobulus, 

 and it is indisputable that they do really agree in several important char- 

 acters, so that it has the appearance that there is really a distinct 

 larval type peculiar to the Temnopleurids (or at least the Temno- 

 pleurinae). Some larval forms taken pelagically and most probably, belong- 



') A classification differing again from both tin- above mentioned has been set forth by 

 .J. Lambert & P. Thiery in their "Kssai de Nomenclature raisonnee des fichinides" (I IV. 

 1909 14). These authors have made a point of working out the natural classification of 

 the Echinoids, taking both the recent and the fossil forms equally into consideration. This 

 is, of course, in itself an excellent principle; in fact, nobody could deny this to be the only 

 natural way * if only the fossil forms were sufficiently well preserved for this use. But 

 this, unfortunately, they are not. When the other authors have confined themselves mainly 

 to the recent forms, it is because they recognize the fact that the fossil forms are imperfectly 

 preserved, so that their characters can only be incompletely ascertained, and accordingly 

 the relation between the recent and fossil forms must remain more or less doubtful. Lam- 

 bert & Thiery, however, have adopted the view that the dassilication of the whole group, 

 recent and fossil forms, has got to be based alone on the characters which can be found in 

 the fossil forms, viz. on the test structure alone. Regardless of all facts known they con- 

 struct their classification strictly on this principle. As, moreover, the nomenclature is worked 

 out on the principle of the priority rule in its strictest, most lilteral sense, it is no wonder 

 that the result is so absurd that it can hardly be taken seriously. 



