DR. WILSON ON THE NERVOUS SYSTEM OF THE ASTERID^. 123 



Fig. 4. Individual cones, a. bird's-eye view ; b. profile; c. lens imbedded in the base; d. nerve entering 

 the apex. 



Fig. 5. Bird's-eye view of individual eyes, with a clear central space. 



Fig. 6. Oblique view of optic bulb and tactile organ, a. nerve-cord ; b. optic bulb, showing very di- 

 stinctly the great number of individual eyes and their arrangement, as well as the clear eye- 

 less portion (c), bounded by the distal rows of cones ; d. tactile organ, very large and with 

 its cavity well marked : the latter may be traced passing onwards behind the bulb. 



Fig. 7- Portion of integument, so reflected from the ganglion as to contain parts of the cords passing to 

 or connected with it. a a. interambulacral cords ; b. arabulacral cord ; d. filaments passing 

 diagonally across to the space between the arms. 



Fig. 8. A second profile view of the bulb and tactile organ, showing the calcareous bridge [a] bearing the 

 whorl of spines ib), underneath which the tactile organ (c) passes to communicate with the 

 water-canal {d). 



Reproduction of a lost Ray. 



Fig. 9. Ambulacral aspect of an amputated ray, at the stage in which the newly reproduced arm is just 

 appearing, a, ganglion of the old ray ; b b. interambulacral cords of the same ; c. dorsal in- 

 tegument, which has curved inwards from behind, in the form of a flap, and united with the 

 skin and other structures of the ambulacral groove. 



Fig. 10. Longitudinal section of a ray, illustrating the first stage towards reproduction : the dotted part 

 in the engraving is the ambulacral nerve-cord and ganglion ; that shaded with horizontal lines 

 represents the water-canal, a. dorsal integument, curving towards the ambulacral groove in 

 the form of a flap ; b. cffical cavity or chamber. 



Fig. 11. Second stage. Union has taken place between the dorsal flap (a) and the ambulacral integu- 

 ment. The ca3cal chamber is continued as a cul de sac between the surfaces of the vertebral 

 plates and the dorsal flap. 



Fig. 12. Third stage. The nerve-cord has sent a prolongation outwards, which is seen resting upon a 

 cutaneous part formed, simultaneously with it, from the dorsal flap. Pigment is deposited at 

 the terminal point of the prolongation ; and the water-canal is continued below it. 



Fig. 1.3. Represents the third stage still more advanced. The pigment-deposit is now seen to contain 

 cones with bright specks at their bases. 



Fig. 14. Illustrates the last stage. The vertebral arches and the suckers now make their appearance. It 

 will be seen, however, that the vertebrae do not continue regularly up as far as the old ones. 

 The two are separated by the ligamentous structure marked x. 



Note. Figures l> 2, .5 & 7 are copied from my Thesis. 



