1894.] The Classification of the Arthropoda. 131 
Sus-Poyitum I—BrancuHiata. 
Arthropods breathing by means of gills (or lungs or trachew 
modified from gills) developed in connection with the append- 
ages; without distinctly differentiated head, with long stomo- 
dum, nephridia persisting in somite II or V (or both), geni- 
tal ducts opening near the middle of the body. Anterior ap- 
pendages all multiarticulate, the basal joints of one or more 
pairs serving as organs of ‘manducation. A chitinous ento- 
sternite and deutova frequently present. 
I hardly think it necessary, each time the limits of a group 
are changed, to give the new combination a new name. Our 
nomenclature is already cumbersome enough, and the slight 
indefiniteness is vastly preferable to the confusion of the other 
course. I have, therefore, retained the term Branchiata for the 
enlarged group, since I regard the lungs and tracheæ of the 
Arachnids as but modified branchie. In only the Edrioph- 
thalmia and certain Phyllopods do we have a distinctly differ- 
entiated “head,” and the head in these groups is not the same 
in its limits. Under the head of nephridia I include the an- 
tennal and shell glands of the Crustacea and the coxal glands 
of the Arachnids and Limulus. The former have been shown 
by numerous observers to be true nephridia, while the obser- 
vations of Laurie (’90) and Lebedinsky (’92), Sturanay (’91), 
are conclusive to the Arachnids. The observations of Gulland 
(85), Kishenouyi (91) and myself (’85 and ’93) would seem to 
settle the matter in the Horse-shoe crab.‘ That the genital 
ducts are to be regarded as modified Nephridia has already 
been shown. Their position is inconstant in the Crustacea, 
varying in some forms with the sexes of the same species. In 
some of the more reduced forms, as the cirripeds, they are 
apparently almost terminal, a condition to be explained by the 
* In my first paper on the development of Limulus, I pointed out that the coxal 
glands of Scorpio and Limulus were apparently homologous with the shell gland of 
the lower Crustacea, since in both cases they open at the base of the fifth pair of ap- 
Pendages. This identification is apparently not pleasing to Professor Claus (86, 
‘Since he has seen fit to ridicule my ideas of homology. I confess that I do not under- 
Stand his objections, and certainly the evidence derived from the neuromeres (admit- 
oo” for metastoma of the Crustacea—c/. Brooks, ’82), seems fully to support my 
Is. 
