HIPPOLYTE VARIANS. 695 



Fig. 10. — Two full " nocturnes," which had, during the day, been brown in 

 colour. X 2. 



EiG. 11. — A nocturne showing on the antennal scales and abdomen a 

 trace of the expanded red and yellow pigment. (In the tables this condition 

 is registered as nocturne in " mid.," "ant.," and "hind," brown.) x 2. 



JFiG. 12. — A black-barred specimen in the nocturnal condition, x 2. 



Fig. 13. — The same in the diurnal colour phase, x 2. 



PLATE 34. 



All the figures in this plate are taken from " red-liners " (see text, pp. 

 606 to 608). 



Fig. 14. — A "red-liner," showing the characteristic bars and stripes of 

 colour. The specimen was outlined with the camera, and the painting made 

 by transmitted light. Hence the (apparent) absence of yellow spots spoken 

 of in the text (p. 609). x 7. 



Fig. 15. — A camera drawing of the chief arteries of the abdomen, taken 

 from a red-lined specimen in all respects comparable to Fig. 14, except that 

 the colour was very faint, and the increased transparency thus aided the 

 definition of the deeper vessels. This figure is to be compared with Fig. 14, 

 in order to show the close agreement between the course of the segmental 

 arteries going to the swimmerets, and the bars of red spots in Fig. 14. In 

 the specimen (Fig. 15) the bars of colour were placed exactly behind the seg- 

 mental artery, which often gave off a small branch to them. The heart was 

 beating about twice a second. No sign of an inferior abdominal artery could 

 be detected, though the passage of the blood from the arterial capillaries into 

 the sinuses was clearly seen. The sternal and thoracic arteries are omitted. 

 X 7. 



Fig. 16. — Three abdominal segments from the tail of a red-liner to show 

 the aorta (Z). A.) ; the pigment attached to the wall of the intestine, and 

 moving during peristalsis {I. P. Z.) ; the pigment associated with the venous 

 intestinal sinus (which is dotted); the dense pigmented sheath (V.S.) round 

 the ventral cord, and the blood-vessel accompanying it. S. W. A swimmeret. 



Fig. 17. — Eye of a red-liner, to show the deep chromatophores in connection 

 with the optic ganglia, and in the more superficial parts of the stalk. X 10. 



Fig. 18. — Eye of a faint red-liner in which, owing to the small quantity of 

 pigment, one can see the ophthalmic artery and its branches, which later inter- 

 digitate with the processes of the large chromatophore between the first and 

 second optic ganglia. Only some of the venous spaces at the proximal end of 

 the stalk are indicated. There are other venous currents from the retina, 

 X 10. 



