PLATE 2. 



Goniocidaris canaliculata A. Agassiz. 

 Figs. 1-3. Falkland Islands. Very young, diam. 1.45 mm. (after Lov6n, 1892, Plate 2, figs. 7-9). X about 26. 



Fig. 1. Ventral view, primordial ambulacra! plates only on the peristome, primordial intcrambulacral plates in basicoronal 

 row, succeeded in the next row by two plates in each area. (Compare text-figs. 23, p. 70; 45, p. 80.) Page 65. 



Fig. 2. Same specimen, side view. Ambulacral plates high hexagonal, pores superposed in each plate. (Compare text-fig. 

 3, p. 54.) Page 58. 



Fig. 3. Same specimen, dorsal view. Oculars exsert, no genital, but one large madreporic pore. One plate fills the 

 periproct (possibly this single plate is an error, p. 174). (Compare adults, text-figs. 73, 74, p. 99.) Pages 101, 172. 



Fig. 4. Southern part of South America. Diam. 23 mm. R. T. J. Coll., 745. X 11. Ambulacral plates at mid-zone 

 low, wide; in young plates beneath the ocular, the height equals the width, as at mid-zone in a young individual, 

 fig. 2. Same specimen as text-fig. 74, p. 99. Page 58. 



Eucidaris tribuloides (Lamarck). 



Fig. 5. Florida. Diam. 5 mm. R. T. J. Coll., 645. X 17. Young ambulacral plates in the placogenous zone are high 

 hexagonal. Page 58. 



Fig. 6. Florida. Diam. 5 mm. R. T. J. Coll., 644. X 21. On the peristome are four or five high, hexagonal ambulacral 

 plates in each column. In the primordial ambulacral row the la, Ila, III6, IVa, V6 are larger than the 16, 116, Ilia, 

 IV6, Va. Two plates in each interradial area of peristome. (Compare adult, text-fig. 46, p. 80.) Page 82. 



Figs. 7-16. Nassau, Bahamas. R. T. J. Coll., 694. Study of the Aristotle's lantern. Page 182. 



Fig. 7. Side view of pyramid. X 2.6. The pyramid has ridges for attachment of interpyramidal muscle; epiphysis has 

 a glenoid cavity, gl., and external and internal tubercles, tu. ., tu. i., for interlocking with brace; tooth grooved. 



Fig. 8. Pyramid, face view. X 2.6. Foramen magnum very shallow; the tooth, epiphyses, braces, and compasses are 

 in place (compare text-fig. 210, p. 184.) 



Fig. 9. Lantern, top view. X 2.6. In area I all parts are in place; in V the compass is removed; in IV the compass and 

 brace are removed and in area II the epiphyses also are removed to show the smooth upper face of the pyramids. 

 (Compare text-fig. 218, p. 191.) 



Fig 10. Half-pyramid, inner view. X 2.6. The pyramidal suture extends nearly to the top, the dental slide reaches only 

 part way to base of foramen magnum as in the Perischoechinoida. 



Fig. 11. Pyramid. X 2.6. Face view, with epiphyses removed. 



Fig. 12. Compass. X 5.3. Top and side views, separated on the line of the suture. 



Fig. 13. Brace. X 5.1. Top view. 



Fig. 14. Left epiphyses of area 2, fig. 9. X 5.4. Top view, to show glenoid cavity, gl., and external and internal tubercles, 

 tu. e., tu. i., for interlocking with the brace. 



Fig. 15. Brace. X 5.1. Lower view, showing condyles, con., and external and internal foramina, /o. e.,fo. i., which inter- 

 lock with the glenoid cavity and tubercles of the epiphyses. 



Fig. 16. Right epiphysis of area 1, fig. 9. X 5.2. Lower view. X in both figures shows the face of sutural contact. 



Goniocidaris canaliculata A. Agassiz. 



Fig. 17. Falkland Islands. Very young (after Loven, 1892, Plate 3, fig. 23). Much enlarged. Lantern inclined, foramen 

 magnum deep, interpyramidal muscles long, as in the Perischoechinoida. (See text-fig. 209, p. 184.) Page 181. 



Phyllacanthus thomasii A. Agassiz and Clark. 



Fig. 18. Hawaiian Islands. Diam. 65 mm. Adapted from A. Agassiz and Clark, 1907, Plate 27. X 1.7. More than 

 one column of non-ambulacral plates in each interradial area of the peristome. Page 82. 



Phormosoma placenta Wyville Thomson. 



Figs. 19-21. Lat. 40 53' 30" N. Lat., 66 24' 00" W. Long. Albatross Station 2530, 956 fathoms. R. T. J. Coll., 778. 



Study of lantern. Page 185. 



Fig. 19. Face view. X 3.2. Pyramids wide-angled, with deep rounded foramen magnum, long interpyramidal muscles, 

 compasses very long. Teeth are grooved and styloid processes extend above the base of foramen magnum as they 

 do in other Centrechinoida and as they do not in the Cidaroida and Perischoechinoida. 



Fig. 20. Dorsal view. X 3.4. Lantern inclined, teeth grooved; in area 1 the tooth is removed to show dental slides; 

 in area V all parts are in place; in area I the compass is removed; in area IV the compass and brace are removed 

 to show the epiphyses; and in area II the epiphyses also are removed to show the top of half-pyramids with the 

 characteristic pits. (Compare Plate 27, figs. 4-6.) 



Fig. 21. Pyramid, side view. X 3.5. Showing the tooth, ridges for attachment of interpyramidal muscle, and epiphysis 

 with glenoid cavity. 



