234 KINGS LEY. [Vol. VI 1 1. 



appendages, possibly the same as that of Croneberg ('80) in 

 Dendryphantes. No preoral ganglion is indicated in his ex- 

 tremely unsatisfactory figures, while his evident desire to find 

 the Hexapod antennae in the Arachnids has possibly influenced 

 his observations. 1 Locy has also figured ('86, PI. XI, Fig. 70) 

 a distinctly three-lobed brain in Agelena. I regret that I have 

 not been able to consult the original plates of Morin's account 

 of the development of the spiders, but as copied by Korshelt 

 and Heider ('92, Fig. 383B) the brain of Theridium consists of 

 four lobes, the posterior of which is apparently the cheliceral 

 ganglion. Kishinouye ('90) also describes the brain of Agelaena 

 as three-segmented. 



In Limulus both Patten and myself have recognized a three- 

 ganglioned cerebrum in front of the ganglia of the chelicerae. 

 None of these cerebral ganglia have been seen by me in a 

 postoral position, but their relation to the ventral chain is such 

 as to justify the supposition that here, as in the Hexapod, there 

 is a very early shifting. 



In the Crustacea I know of no observations of evanescent 

 appendages or neuromeres, unless, possibly in the case of the 

 metastoma. So far as observations go the series is, appar- 

 ently : first, the procephalic lobes ; second, a pair of ganglia in 

 front of the antennulae, figured by Bumpus ('91, PI. XVII, Fig. 

 i) then, antennulae, antennae, etc. As to just where the line 

 between preoral and postoral is to be drawn is uncertain. That 

 the antennulae of the Crustacea are to be classed in the primi- 

 tively postoral series is evidenced by several facts. In the first 

 place, they are placed by all observers at first in a paraoral if 

 not a postoral position, and in a direct continuation of the post- 

 oral appendages. Secondly, the evidence presented by Apus is 

 clearly understood upon the basis of a complete transfer of the 

 ganglia and appendages to a preoral position. In the adult the 

 ganglia of the antennulae {cf. Pelsencer, '85) are fused with the 

 cerebrum, while the course of the nerves (see Zaddach, '41, PL 

 III, P^igs. I and 5) shows distinctly a transfer of the structures 



1 In the light of the observations of Carriere and Wheeler his discovery does 

 not help matters, for there is still a somite lacking, to make the parallel exact 

 from his standpoint. 



