1 894-] ENTOMOLOGICAL NEWS. 213 



ON A CLASSIFICATION OF ARTHROPODS. 



By Nathan Banks. 



Prof. J. S. Kingsley has recently given a classification of Ar- 

 thropods (Tuft's College Studies, No. i; and Am. Nat. 1894, pp. 

 188-220). Though entomologists do not often care for such 

 things, still the opinions of the "general biologist" may some- 

 times merit attention. Prof. Kingley's classification is based on 

 embryological data where it is obtainable. He divides the Ar- 

 thropods into three great groups: Branchiata, Insecta and Dip- 

 lopoda, leaving unplaced the Pantopoda, Pauropoda, Tardigrada, 

 Malacopoda and Linguatulina. 



For many years it has been plain that the Arachnida were more 

 closely related to the Crustacea than to Insecta. This fact has 

 been the death of the old group Tracheata. But, I think that 

 with the disappearance of the nam.e Tracheata should also go that 

 of Branchiata; for the latter is certainly more uncharacteristic of 

 the forms placed under it than is the former. The Branchiata 

 are divided into the Crustacea (including Trilobites and the true 

 Crustacea) and Acerata (including Limalus and Arachnida). In- 

 secta are separated into two groups (classes): Chilopoda and 

 Hexapoda. Beyond this the classification is but little developed, 

 except in the Crustacea, where he follows Grobben. The most 

 interesting part of the paper is the attempt to homologize the 

 appendages of the various groups. The results are, that the first 

 appendage (antennae) of Hexapods, he finds is not represented 

 elsewhere in the Arthropoda. That the second appendage of 

 Hexapods (probably labrum, as it is cephalad of the mandibles) 

 is not represented in either the Arachnida or Limulus, but is ho- 

 mologous with the antennules of Crustacea. After this the ap- 

 pendages follow in regular order. One is not surprised that after 

 such conclusions Prof Kingsley is almost ready to doubt the 

 unity of the Arthropoda. One reads (p. 20, Tuft's College 

 Studies, No. i) that the Arthropoda have "typically, a pair of 

 appendages to each somite." But there is not a word of ex- 

 planation why two pairs of cephalic appendages have disappeared 

 in both Arachnids and Limiihis, and one in the Crustacea. Ap- 

 pendages near the mouth appear to be generally desirable and 

 useful in Arthropods. 



The purpose of the evolutionist I take to be the search for 



