THE EMBRYOLOGY OF A SCOEPION. 141 



Fig. 50. — Longitudinal section through the lateral eye, showing its forma- 

 tion by a thickening of the hypodermis. X if^. 



Fig. 50a. — Section through a somewhat older lateral eye in which the 

 inpushing of the hypodermis has disappeared, x ^^. 



PLATE XVIII. 



Fig. 51. — Longitudinal section through the tail end of Stage M, showing 

 the poison-gland, proctodaeum, intestine, &c. x -\-. 



Fig. 52. — Transverse section through the posterior end of the body, showing 

 the intestine, with the Malpighian tubes, the heart, &c. x -\2- . 



Fig. 53. — Transverse section a little further foward than Fig. 52, showing 

 the intestine, which has not yet closed into a tube. X -Y- • 



Fig. 54. — Section through the coxal gland of a newly-hatched scorpion, 

 showing the opening to the exterior, &c, X ■^- . 



Fig. 55. — Longitudinal section through a gill-book of a newly-hatched 

 scorpion, x ^^. 



Fig. 56. — Longitudinal section through the central eye of an embryo a short 

 time before hatching, showing the closure of the cerebro-optic invagination 

 and the three layers of the eye. x -\^- . 



Fig. 57. — Longitudinal somewhat oblique section through the central eyes 

 of a newly-hatched scorpion. X -f^. 



Fig. 58. — A few cells of the same eye more highly magnified, and showing 

 the inpushing in the vitreous layer. 



Figs. 58, a, b, c. — Transverse sections through the same eye at different 

 levels. 



Fig. 59. — Section through the lateral eyes of a newly-hatched scorpion. 



V 2 22 

 /K -J—. 



Fig. 60. — Transverse section through the posterior part of the body of a 

 newly-hatched scorpion, showing the fully-formed intestine, the Malpighian 

 tubes, the nerve-cord, and the trabecular tissue filling up the coelomic space. 



V 2_2_2_ 



Fig. 61. — Transverse section through the intestine further forward, where 

 it is not yet properly formed, showing the irregular hypoblast cells and yolk- 

 spheres. X ^1^. 



