XXXIV LIST OF ENGRAVINGS. 



Fig. Page 



394 Magnified view of the labyrinth detached from the sur- 



rounding parts, (Breschet) 427 



395 Interior structure of the labyrinth, (id.) 428 



396 Membranous labyrinth, with its nerves, (id.) 428 



397 Cretaceous bodies in the labyrinth of the Dog, (id.). . 428 



398 Ditto in that of the Hare, (id.) 428 



399 Organ of hearing in the Lobster, (Carus) 435 



400 Groove in the sac of the former, (id.) 435 



401 Organ of hearing in the Astacus fluviatilis, (id.) 435 



402 Interior view of the same, (id.) 435 



403 Membranous labyrinth of the Lophius piscatorius, (id.) 438 



404 Organ of hearing in the Frog, (Bell) 430 



405 Ear of the Turkey, (Carus) 430 



406 Diagram illustrating one mode of obtaining images of 



objects, (original) 450 



407 Simple Camera Obscura 451 



408 Law of the refraction of a ray of light 454 



409 Convergence of rays to a focus 455 



410 Convergence by a double convex lens 457 



41 1 Spherical aberration 458 



412 Variations of focal distance, consequent upon variations 



of divergence of the incident rays 459 



415 Horizontal section of right human eye magnified, (Home) 461 



416 Straight and oblique muscles of the eye-ball 464 



417 Lacrymal apparatus 467 



418 Eye of Helix pomatia, (Muller) 481 



419 Stemmata of Caterpillar, (Marcel de Serres) 484 



420 Eye of the Scorpio tunensis, (Muller) 484 



421 Conglomerate eyes of Julus terrestris, (Kirby and 



Spence) 484 



422 External magnified view of the compound eye of the 



Melolontha vulgaris, (Straus Durckheim) 487 



423 Ditto of that of a Phalena 487 



424 Section of the compound eye of the Libellula vulgata, 



magnified, (Duges) 487 



425 Highly magnified view of the outer margin of the pre- 



ceding section, (id.) 488 



426 Portion of the section of the eye of the Melolontha 



vulgaris, (Muller) 488 



