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and in process of growth ; 36, 39 — 41, completely developed plates, the holes filling with lime until 
in 41 over j of the holes have become filled to pits (indicated by shading) ; 34, incomplete plate 
of large size. In 34, 39, 40 the basic developmental Types a and b may be noted surrounded 
with additional peripheral holes. 
Figs. 42 — 49 illustrate the development of the table. 
Fig. 42. Eod with forked end, Anlage of disc. 
Fig. 43. Appearance of the 4 vertical rods. 
Fig. 44. Ends of the 4 prongs begin forking. 
Fig. 45. Variate with 5 prongs and 5 vertical rods. 
Fig. 46. Formation of primary and peripheral holes of disc and growth of vertical rods. 
Fig. 47. The 4 primary and 2 of the secondary holes completed ; joining of vertical rods by transverse 
beams to form crown ; appearance of teeth. 
Fig. 48. Nearly developed table. 
Fig. 49. Fully developed table. 
Figs. 50 — 62. Series of disc variates. To show the feature of the disc each is drawn with the vertical 
rods bearing the crown removed at their bases. Figs. 50 — 54 have the 4 primary holes indicated 
with developing secondary holes as follows : 50, none ; 51, 1 ; 52, 2 ; 53, 3 ; 54, 4. 
Figs. 55 — 62 show variation in the number of peripheral holes (secondary and tertiary) from 4 — 11. 
Figs. 63 — 74. Series of discs (drawn as above) showing variation in the number (1 — 10), form and size 
of spines, accompanied by a modal distribution of holes (64 — 67) or by an abnormal number and 
distribution of holes ((13, 68 — 74). In 72, with a nearly circular disc, there are 8 vertical rods with 
a secondary hole for each rod. 
Plate V. Calcareous spicules of the body-wall and the pieces of the calcareous ring. 
Figs. 77, 78, 80, 83, 85, 87, 90—98 from U.floridnna ; 75, 76, 79, 81, 82, 86, 88, 89 from //. aim. 
Figs. 77, 78, 80, 83—85, 87, 90—92 dorsal ; 75, 76, 79, 82, 86, 88, 89 ventral. 
Figs. 75— 92, x 260 ; Fig.s. 93—96, x2i ; 97,98, x 9i. 
Figs. 75 — 86. Series of crown variates. The underlying vertical rods are indicated by dotted outlines. 
Fig. 75, normal type with 12 teeth; 76, 2 teeth at each of 3 corners, 3 at the 4th and 1 on a 
transverse bar ; 77, extra tooth on a transverse bar ; 78, 3 extra teeth on transverse bars ; 
79, triangular variate with extra tooth on each of 3 transverse bars; 80, incomplete crown, 
1 corner lacking ; 81, triangular variate without central hole ; 82 — 84, abnormal variates ; 85, 
incomplete crown from the failure to fuse of the two processes which would normally make a trans- 
verse bar ; 86, incomplete crown with some teeth lacking, 2 bifid and 1 extra vertical rod. 
Fig. 87. Complete disc, 5 vertical rods and no crown. 
Fig. 88. Disc and 89 crown, of table with 7 vertical rods. 
Fig. 90. Disc and 91 crown, of abnormal variate. 
Fig. 92. Reduced table with only central part of disc and the spire present. 
Figs. 93 — 96 from calcareous ring of the adult. 
Fig. 93. Eadiale, usual form. 
Fig. 94. Kadiale, with anterior border notched toward the sides. 
Fig. 95. Inter-radiale. 
Fig. 96. Fused ventral and left ventral radialia, the intervening left ventral inter-radiale included 
in the compound piece. 
Figs. 97, 98. More regular and delicate pieces of the calcareous ring of the young. 
Fig. 97. Radiale. 
Fig. 98. Inter-radiale. 
Fig. a. See for explanation p. 248. 
