ox THE LATKlîAL EYES OF SPIDEIÎS. 



108 



ail allied ofdei-, Scorpioiiido:!. Pai'ker, however does not «eem to 

 consider this interesting' fact as of much vahie, il'lie has not indeed 

 o^■erl^Joked it. 



Lankcster and lîonrno* arriNcil at rlic same (-(ynchision as \ have 

 done, from a study of the strii<:ture of the eyes of the adult Liinulus 

 and of Scorpio: hut thev Avaiited the emhryologi(';d proof. Since 

 tliey Mrotc miidi work has l)een done on tln' de\ clopment of spiders, 

 scorpions and Lhiiiihn^ : but no one till now has coiiiii'incil their 

 conclusion. 



The facts that the number and the relative position of the simple 

 eyes of s})iders and scorpions are very varialüe and that the eyes are 

 j)laced more closelv together in the emln-yonic tliau in latei* stages, 

 sj)eak in fa\oui' of oin' eonclusion. 



The separation and modification of the ommatidia of a compound 

 eye into simple eyes ai'e ])robably the ctfects of t lie change of the 

 animal's liabit— from that of wandering about in pursuit of prey to 

 that of Iving in Avait for it. 



The lateral eyes of spiders Avere called " Augen mit pr;il)a(allären 

 Kern " by «J raber, and '' Xebenaugen " by 15ertkau ; but -as they are 

 homologous ;is a whole with the lateral eyes of scorpions and with the 

 lateral conpound eyes nï LiiiiuJus, 1 propose to call them laU'val eijes as 

 \ have done in this paper. 



* Lankestor :i.u<l Boiu-ue — 'ZVc Minnie Strticturc of thi' f.iifrni! 'iiul the Cfittrnl Eijeit of 

 Sroriiio and of Linin/iif. «.^nart. Join-. Mii'. S»;. XXIIT. 



