CLASS 



116 



["SECT. 



I. Cidaris* (1) 



I. Anocysti. 



I II. 



r 



(2) 



II. Catocysti. 



GENUS. 



C I. Miliarcs. 

 II. Variolates. 



III. Mammillatce. 



IV. Coronales. 

 V. Corollares. 



VI. Asterizantes. 

 VII. Assulutce, 

 VIII. Botryoides. 

 IX. Toreumaticce. 



I. ComK. 

 II. Discoides. 



III. Pleurocysti 



I. Fibulae. (3) 



II. Cassides. (4) 



III. Scttfa. (5) 



IV. Placentae. (6) 



I. Arachnoides. (7) 

 II. Corda marina (8) 



S 1. JJI tdSl. 



^-III. Ova marina. (9) J II. Brissoidcs. 



II. Galeolae. 

 V I. Anyularia. 

 t II. Orate. 

 T I. Mellitce. 

 N II. Laqance. 

 I III. 



I. Spatangi. 

 II. Spatagoides. 



* As most of the terms employed for these sections have beeu since 

 adopted as the names of genera, it was thought proper to subjoin the 

 general characters of the substances to which they were here applied. 



( 1 .) Cidaris. Turban- formed, with areas ornamented with prominent 

 tubercles and porous ambulacrse ; the mouth in the centre of the base, 

 the vent in the apex. 



(2.) Clipeus. Hound, shield- formed ; the mouth nearly in the centre 

 of the base ; the vent at nearly the same distance on the other side of 

 the centre of the apex. 



(3.) Fibulce. Conical or discoidal ; the mouth in the centre of the 

 base, the vent in the margin. 



(4.) Cassis. Helmet-formed; the mouth and vent at the opposite 

 ends of the base. 



(5.) Scutum. Angular or ovate shield-formed ; the ambulacra cre- 

 nated and porous, disposed in the form of five petals ; the mouth in the 

 centre, and the vent near the margin, in the base. 



(6.) Placenta. Nearly flat ; the upper surface sligfhtly convex ; 

 lower flat ; margin acute; the mouth in the centre; vent nearly mid- 

 way between the mouth and the margin. 



(7.) Arachnoides. Placenta-formed ; the mouth in the centre ; the 

 vent square on the upper surface, at the margin. 



(8.) Corda marina. Cordiform ; the smaller end truncated, the 

 mouth labiated, near the larger end of the base ; the vent in the trun- 

 cated smaller end. 



(9.) Ova marina. Egg-formed; smaller end truncated ; mouth labiated 

 near the larger end of the base ; the vent in the truncated smaller end. 



