154 CLASS IV. 



Nudeolites LAM. Body ovate or cordate, convex, sub-irregular. 

 Ambulacra five, extending radially from the vertex to the base, not 

 interrupted. Anus superior, near the margin. 



All the species are fossil, partly from the secondary, partly from the 

 tertiary formation. 



Cassidulus LAM. Body irregular, elliptic, ovate, or subcordate. 

 Ambulacra five, circumscript, resembling a pentapetalous flower. 

 Anus superior, near the margin. 



This genus also consists of fossil species from different formations ; ex. 

 gr. from the chalk formation is Cassidulus lapis cancri LAM., FAUJAS DE 

 ST FOND, Besch. van den St. Pietersberg, PL 30, fig. i ; BRONN Lethcea 

 geogn. Tab. xxix. fig. 20. 



Fibularia LAM. Echinocyamus LESKE. Body sub-globose, with 

 outline oval or orbicular. Ambulacra five short, circumscript. Anus 

 inferior near the mouth, or median between the mouth and the 

 posterior margin. 



Sp. Fibularia, ovulum LAM., GUERIN Iconogr. Zooph. PL in. fig. 5, Echinocy- 

 amus pusillus MUELL., FORBES Brit. Starf. pp. 175, &c. From the Atlantic 

 Ocean, of the size of a pea. Amongst the foreign species, according to 

 VAN PHELSUM, mostly American, we note Fibularia craniolaris, V. 

 PHELSUM Gewelvslekken Tab. i. f. 16 35. Also in the chalk-formation 

 and in tertiary deposits species of this genus occur. 



Echinoneus LESKE, LAM. Body sub-ovate or orbicular, sub- 

 depressed. Ambulacra inscribed radially in ten furrows from the 

 summit to the base, not interrupted. Anus inferior, oblong, near 

 the mouth. Genital pores four. 



Sp. Echinoneus semilunaris LAM., GUER. Iconogr. Zooph. PL in. fig. i, Cuv. 

 R. Anim.ed. ill., Zoophytes, PI. xiv. fig. i, from the West Indian Sea, &c. 

 Of this genus no fossil species are known. 



Clypeaster LAM. Body oval or sub-angular. Ambulacra cir- 

 cumscript radiating from the summit, resembling a pentapetalous 

 flower. Anus inferior, near the margin, or in it. Genital pores 

 mostly five. 



Sp. Clypeaster rosaceus, Echinus rosaceus, L. KLEIN Dispos. Echinod. Tab. 

 xvii. fig. A, Tab. xvni. fig. B, BLAINVILLE Actinol. PL xvn. ; from the 

 Indian and Japan Seas. The shell is thick, and parted internally by 

 pillars ; comp. the figures in KLEIN 1. 1. Tab. xxviii. XXIX. Fossil 

 species also from the tertiary formations are known. 



