518 Mr. H. M. Bernard on the 



between tlie ocular tubercle and the lateral edge of the dorsal 

 surface. 



In Tlielyplwnus the ocular tubercle appears to persist near 

 its orip;inal position, while the lateral eyes have moved further 

 back tlian in Phrynus^ and are close to the lateral edge of the 

 dorsal surface. 



In Scorpio the median eyes persist, as a rule, upon an ocular 

 tubercle, which has, however, in many cases travelled back 

 along the suture between the cej)halic lobes. The accessory 

 eyes appear to have travelled off sideways while the ocular 

 tubercle still occupied its original position, i. e. was at the 

 anterior end of the suture between the cephalic lobes. They 

 are found along the fronto-lateral edge of the dorsal surface. 



In the Chernetidai the median eyes appear to have atrophied, 

 while the lateral eyes persist in one or two pairs at the edges 

 of the dorsal surface. 



In the Phalangidie, as a rule, only the median eyes are 

 developed ; but lateral eyes also occur in rare cases, although 

 those iigured by Blanchard * have been shown to be glands. 



In the Galeodida3 we have the median eyes on a sharply 

 demarcated ocular tubercle situated in the original position, 

 ,that is, at tlie anterior end of the suture between the cephalic 

 lobes. The accessory eyes apparently, as in Scorpio^ 

 wandered off laterally, i. e. in the transverse plane, thus 

 retaining their frontal position. But the enormous develop- 

 ment of the mandibles, which is doubtless a secondary 

 acquirement, together perhaps with the development of the 

 curious foldings of the cuticle (to form the buttresses upon 

 which the mandibles rotate), have led to the shifting of the 

 eyes down, over the edge of the dorsal surface, on to the lateral 

 surface, so that they now look downwards and forwards 



In spirit-specimens the eyes themselves appear, when 

 looked at with a pocket-lens or even with the naked eye, as 

 whitish patches, which vary greatly in form and arrange- 

 ment. In fig. 1 they are seen to have run together to form 

 a long oval patch ; in fig. 2 there are two eyes — the anterior 

 an oval, and the posterior a minute, nearly circular mass o{ 

 pigment ; whereas in fig. 3 they appear about ecpuiUy (\i;w<i- 

 loj)ed. 1 have not yet seen more than two on each side. 



That these eyes are atrophying I think is apparent from 

 their irregular forms and, perhaps, from their position. But, 

 on the other hand, in some cases ((;/." lig. 3) they have a well- 

 developed ganglion and regularly arranged retinal cells, the 



* ' Les Aracliiiiili's,' i>l. xxx. 



