Plate VII. 



Fig. I. Echinosigra (Pourtalesia) pliiale, the sub-oral region of the test. I 3/ 1 . Not the same specimen 

 as that represented in PL VI. Figs, i — 2, 7. The limitation of the ambulacral plates IV. a. 1. 

 b. 1 could not be made out quite distinctly, but it is certain that a. 1 was larger than b. 1. 



— 2. Pourtalesia Jeffreysi, opened from the side. The loop of the intestine has been bent backwards 



in order to show the course of the stone canal, g. Genital organs. 1 / I . 



— 3. Pourtalesia Jeffreysi, part of the stone canal with the axial organ. l6 /j. 



— 4. — opened from the side, showing the intestine in its natural position; g. the 



genital organs of the right side, bent outwards. '/,. 



— 5. Echinosigra (Pourtalesia) paradoxa, the suboral region of the test. r 3/ x . 



— 6. Urechinus naresianus, female genital organs. 2 / : . 



7. Echinosigra (Pourtalesia) phiale, apical system and adjoining parts of the test. 



21/ 



/i- 



— 8. Urechinus naresianus, opened from the side. The loop of the intestine has been bent back- 



wards in order to show the course of the stone canal. I / 1 . 



— 9. Plexechinus hirsutus, apical region of the test. From a specimen 6 mm in diameter. No pores 



to be distinguished in the ocular or ambulacral plates. '3/^ 



— 10. Echinosigra (Pourtalesia) paradoxa, female genital organs, g, and stone canal, s. '"/p 



— 11. Pourtalesia Jeffreysi, female genital organs. z /i- 



— 12. male genital organs. On the stone canal (s) is seen a little swelling, the 



axial organ. 2 / 1 . 



— 13. Urechinus naresianus, opened from the abactinal side; the intestine is represented in its natural 



position. I I I . 



— 14. Pourtalesia Jeffreysi, opened from the actinal side ; the intestine is represented in its natural 



position. The two siphones are distinct. t / I . 



— 15. Urechinus naresianus, opened from the abactinal side. The intestine bent aside in order to 



show the two siphones. t / 1 , 



— 16. Echinosigra (Pourtalesia) paradoxa, anterior end of the test, opened from the side. g. Male 



genital organs, s. stone canal, ce. oesophagus. 6 / 1 . 



— 17. Spatagocystis Challengeri, tube foot. I2 5/ r . 



— 18. Echinosigra (Pourtalesia) paradoxa, tube foot. 1Z5 / I . 



— 19. Plexechinus hirsutus, actinostome and surrounding parts of the test. The plates of the actino- 



stome have been drawn from another specimen; the specimen, from which the plates of the 

 test were drawn, had the buccal membrane bent inwards, so that its plates could not be 

 made out. 8 /i- 



— 20. Plexechinus hirsutus, apical plate and part of the odd anterior ambulacrum. In the apical 



plate a small madreporic pore and two larger genital pores are seen. I 5/ I . 



— 21. Pourtalesia Jeffreysi, tube-foot. ^s/j. 



