72 



K. KISHINOUYE. 



the posterior median eyes in connection with the brain in .spiders is 

 quite analogous to the simihir process in scorpions as observed by 

 Kowalevsky and Schulgin. This interesting relation was not observ- 

 ed by Locy who studied the spider, or by Parker* who studied 

 the scorpion. 



Hitherto these eyes were called the anterior median eyes ; but 

 morphologically speaking, this nomenclature is not correct. For all 

 the eyes of spiders are formed in reality in the Neutral jjhite, never in 

 the dorsum, and gain their apparently dorsal position in later stages 

 only by the bending upward of the ventral plate. Hence, in this last 

 position the eyes that composed the ])osteri(jr row in the ventral 

 position come to occupy the anterior position, while those that formed 

 the anterior row in the ventral position are thrust further backward 

 by the curving upw\ard of the ventral plate and thus become the 

 apparent posterior row. Hence those I called the posterior median 

 eyes are in the apparent anterior row of the adult. 



The three remaining pairs of eyes are formed later than the 

 posterior median pair and in a different manner. Their first traces 

 are the local thickenings of the ectoderm of the cephalic region 

 Anterior lateral eyes (A. L. E.) ai)pear above the lateral vesicle (PI. 

 XV, fig. 46). 



At this time the lateral vesicles are c<jnipletely cut off from the 

 general ectoderm (PI. XV, figs. 44, 46). Their walls are thick and 

 their lumen is cons[)iGuous. In development and position they ^'ery 

 much resemble the eyes of Peripatus. 



The chelicera3 are now two-segmented. They have shifted their 



position a little anteriorly and have approached toward the median 



line (PI. XIII, fig. 21). Their ganglia are placed at the sides of 



the stomodteum and form tlie commissural part between the supra- 



* Parker— The Eyes in Scorpions, Bull. Mus. Comp. Zool. XIII. 



