Il6 NATURAL SCIENCE. February, 



there is tolerable unanimity touching the isolated position of Pevipatus. 

 Even on this subject, however, there are gradations of opinion, from 

 that held by Mr. Stebbing, who would wait for further evidence 

 before expelling the Malacopoda from the rest of the Arthropoda, to 

 that of Dr. Hansen, who boldly maintains that Pevipatus is nothing 

 but a specialised chaetopod. Mr. Carpenter and Professor Claus, on 

 the other hand, regard it as a type that early diverged from a common 

 arthropod stock, structurally in advance of the grade of organisation 

 characteristic of the higher Annelida. These two authors therefore 

 regard the Arthropoda as a homogeneous, monophyletic assemblage, 

 while Messrs. Kingsley, Laurie, Pocock, and Bernard, who hold that 

 there is no common ancestor for Pevipatus and, say, the Crustacea 

 nearer than the Chaetopoda, are compelled to conclude that the 

 " sub-kingdom " is polyphyletic. This also appears to be the view of 

 Dr. Jaworowski, and also, as we have good reason to suppose, of Dr. 

 D. Sharp, The balance of opinion seems therefore to be in favour of 

 a plural origin for the Arthropoda. 



Concerning the relationship of the various classes it is noteworthy 

 that Messrs. Claus, Carpenter, Bernard, and Kingsley admit no 

 affinity between Pevipatus and the Tracheata Antennata, while Pocock 

 and Laurie lean to the opinion that the two may be related, an opinion 

 which was long ago tacitly expressed by Lankester when he estab- 

 lished for them his group Ceratophora. 



Again, Mr. Bernard seems to stand alone in his view as to the 

 independent annelid origin of the Arachnida, Messrs. Claus, Kingsley, 

 Pocock, Laurie, and Carpenter placing this class in close proximity 

 to the Xiphosura, as was originally done by Lankester. But, while 

 Pocock, Bernard, and Claus consider the Xiphosura to be the lineal 

 descendants of the Trilobita, Professor Kingsley places the latter 

 alongside the Crustacea and the Xiphosura at a distance under the 

 Arachnida. This tangle of opinion is still further increased by the 

 association of the Trilobita with the Crustacea by both Mr, Bernard 

 and Mr. Pocock, and the separation of the two as of independent 

 origin by Professor Claus. Mr. Laurie preserves a judicious, but 

 provoking silence on the topic of the Trilobita. 



Most of our contributors speak of the Myriopoda as a recognisable 

 and natural assemblage ; but while Messrs. Pocock and Kingsley 

 repudiate the notion and classify the Chilopoda with the Hexap da, 

 Kingsley does not admit the affinity that Pocock thinks traceable 

 between the Diplopoda and the two classes now mentioned. 



The opinions of Drs. Hansen and Jaworowski, though mentioned 

 in connection with Pevipatus, dififer so entirely from those of the other 

 contributors as to be of necessity treated apart. Hansen, who, 

 perhaps wisely, has nothing to say concerning descent, regards the 

 Arachnida and Pantopoda as isolated classes of the Arthropoda, and 

 the Crustacea, Myriopoda, and Insecta as closely allied, this unique 

 conclusion being based upon the structural resemblances in the 



