754 PROFESSOR WYVILLE THOMSON ON THE ECHINOIDEA OF THE 
PLATE LX VII. 
Calveria fenestrata. 
Fig. 1. A portion of an ambulacral area from the oral surface of the test. X 2. 
Fig. 2. A portion of an interambulacral series from the same part of the test. X 2. 
Fig. 3. A part of an interambulacral series from the apical surface of the test near the 
edge of the periproct. x 2. 
Fig. 4. A portion of the base of one of the larger spines, x 20. 
Fig. 5. One of the tetradactyle pedicellarise. X 35. 
Fig. 6. A like pedicellaria. x 60. 
Fig. 7. A tridactyle pedicellaria. x 40. 
Figs. 8, 8 a. An ophiocephalous pedicellaria. X 60. 
Fig. 9. One of the tube feet from the oral surface of the test. 
PLATE LXVIII. 
Echinus microstoma. 
Fig. 1. General view of the test from above. 
Fig. 2. A portion of the test removed to show the form of the auricles and the position 
of the dental pyramid. 
Fig. 3. Dental pyramid, x 2. 
Fig. 4. One of the small flattened spines from the neighbourhood of the mouth. X 6. 
Fig. 5. A pedicellaria. X 25. 
Fig. 6. A pedicellaria, the valves provided with large external fleshy lobes containing 
curved calcareous spicules. X 40. 
Fig. 7. The separated valves of a pedicellaria of this form. X 50. 
Fig. 8. Stems of pedicellarise with curved calcareous spicules imbedded in their investing 
membrane. X 80 ; the separate spicule X 100. 
Fig. 9. A portion of one of the tube feet, showing the curved spicules imbedded in the 
wall. X 60. 
Fig. 10. A portion of the wall of the intestine. X 100. 
Echinus elegans. 
Fig. 11. View of the test from above. X 2. 
Fig. 12. One of the primary spines. X 5. 
Fig. 13. The dental pyramid. X 4. 
Fig. 14. The dental pyramid of Echinus Flemingii , introduced for comparison, x 2. 
