1894.] The Classification of the Arthropoda. 119 
cal rather than morphological, and that their emphasis tends 
to obscure true relationships upon which alone a natural sys- - 
tem can be based. Since Lankester wrote, most students of 
Arachnid morphology and every one (excepting Professor 
Packard) who has investigated the structure or ontogeny of 
Limulus, have endorsed the general conclusion that Limulus 
is closely related to the Arachnids. 
This being the case, Lankesters’s later views upon the sub- 
division of the Arthropoda possess a peculiar interest. In the 
ninth edition of the Encyclopedia Britannica, article “Zoology,” 
he gives the following arrangement: 
Branch Arthropoda. 
Grade 1, Ceratophora. 
Class I, Peripatidea. 
Class II, Myriapoda. 
Class III, Hexapoda. 
Grade 2, Acerata. 
Class I, Crustacea. 
Class II, Arachnida. 
Class IIT, Pantopoda, 
Class IV, Tardigrada. 
Class V, Linguatulina. 
Professor Claus is apparently not so radical in his ideas. I 
fail to make out from his various polemical articles (86 * *., 
87 *) exactly what his later views are, but in the fourth 
edition of his Lehrbuch (’88)—the fifth edition is not at hand 
—there is such a lack of regularity in the subordination of 
type, headings, etc., that it is difficult to ascertain his opinions. 
As I interpret him, he has the following scheme : 
Arthropoda. : 
Class 1, Crustacea. 
Sub-Class I, Entomostraca. 
Sub-Class IT, Malacostraca. 
Gigantostraca. 
Merostomata. 
Xiphosura. 
Class II, Arachnoida. 
Class III, Onychophora. 
