Plate VII. 



Fig. I. Echiiiosigra (Pourtalesia) phialc, the sub-oral region of the test. '3/i. Not the same specimen 

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

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



2. Pourtalesia Jejfrcysi, 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. Vi- 



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



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



genital organs of the right side, bent outwards, '/i- 



— 5. Echiiiosigra (Pourtalesia} paradoxa, the suboral region of the test. '3/j. 



— 6. Urcchinus naresiamis, female genital organs, ^l^. 



— 7. Echiiiosigra (Pourtalesia) phiale, apical system and adjoining parts of the test. ^'/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. 



— g. Plexcchinus hirsutus, apical region of the test. From a specimen 6™"" in diameter. No pores 



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



— 10. Echiiiosigra (Pourtalesia) paradoxa, female genital organs, g, and stone canal, s. '°/,. 

 — -11. Pourtalesia Jeffreysi, female genital organs, ^/j. 



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



a.xial orgau. 2/,. 



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



position, '/j. 



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



position. The two siphones are distinct, '/j. 



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



show the two siphones. 'y'j. 



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



genital organs, s. stone canal, oe. oesophagus, ^i. 



— 17. Spatagocystis Challengeri, tube foot. "S/j. 



— 18. Echinosigra (Pourtalesia) paradoxa, tube foot. ""^ji. 



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



stome have been drawn from another sj^ecimen; 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. 7i- 



— 20. Plcxechinus 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. '5/j. 



— 21. Pourtalesia Jeffreysi, tube-foot ^^^l■^. 



