L 



STRUCTURE OF THE EYES. 411 



fifty or more in each ring, the interspaces being free 

 from them. (Fig. 8.) The capsules are not regularly- 

 arranged. They are minute egg-shaped bodies, with 

 a cavity of similar form towards the larger end, which 

 I presume to contain the projectile thread. (Fig. 9.) 

 But owing to the minuteness of the capsules, their 

 longer diameter not exceeding ^^th of an inch, the 

 plates of the compressorium would not act upon them 

 so as to effect the propulsion of the filament in a 

 single instance that I could detect, even with many 

 trials. 



The secondary or small tentacles have not in general 

 the capsules disposed in regular rings, but only a few 

 scattered throughout, with the exception of their tips 

 which are composed of a globose dense assemblage of 

 these organs. A few are scattered through the sub- 

 stance of the peduncular stomach. 



The visual organs (fig. 5) are from -^to -^thinch 

 in diameter. They appear to be composed of gelatin- 

 ous matter, with a central oval cavity about -^th 

 inch in diameter, in which at one end is a globular, 

 highly refractile, crystalline lens, about j^th inch in 

 diameter. On graduated pressure being applied, the 

 vesicle is seen first to flatten, then the cavity ; but 

 when the plates of the compressorium act on the lens, 

 it breaks into pieces like a crystal, and usually with 

 a fracture that radiates from its centre. The frag- 

 ments do not differ in appearance from the entire 

 spherule. 



