L. Agassiz on the Echinodennata. 305 



(Scut. Parm., Lam.) — E. placunarius, Ag. (Scut, placun., Lam.) — E. lafis- 

 simus, Ag. (Scut, latissima, Lam.) — E. Rumphii, Ag. (Echinodis. Humph., 

 De Bl.) 



13. Scutella, Lam. and De Bl. (Echinodiscus, Leske and Gr. — 

 Mellita and Rotula, Kl. — Lag ana, De Bl.) — Shell flattened, circular, 

 margins thin ; ambulacra as in Clypeaster, but in proportion larger ; 

 anus inferior. The species are very numerous, some fossils of the 

 tertiary formation, and some living. 



Sc. altavillensis, Defr. — Sc. gibberula, M. de S. — Sc. hispanica, Defr. — 

 Sc. nummularia, Defr. — Sc. occianta, Defr. — Sc. striatula, M. de S. — Sc. 

 subrotunda, Lam. — Sc. porpita, Bory. — Sc. orbicularis, Lam. — Sc. ovalis, 

 Ag. (Lag. oval., Brug.) — Sc. Integra, Brug. — Sc. inaurita, De Bl. — Sc. au- 

 rita, De Bl. — Sc. dentata, Lam. — Sc. radiata, Seba. — Sc. digitata, Lam. — 

 Sc. octodactyla, De Bl. — Sc. hexapora, De Bl — Sc. pentapora, De Bl. — Sc. 

 bipora, Lam. — Sc. tetrapora, De Bl. — Sc. emarginala, Lam. 



III. The Cidarites constitute a family, the most prominent cha- 

 racter of which is the spheroidal form of the shell, which is beset 

 with two kinds of spines ; the first larger, situated on large mammillae; 

 the others smaller, surrounding the base of the first, or covering the 

 ambulacra. The mouth is central, at the inferior surface of the 

 disc ; the anus, which is diametrically opposite to it, is situated at 

 the summit of the disc, and opens between the small laminae sur- 

 rounding it, opposite and sometimes very near to the posterior am- 

 bulacral space. 



1. Cidaris, Lam. and Auct. — Ambulacra narrow, covered with 

 small, compressed spines, interambulacral spaces large, each of their 

 plates being surmounted with one large perforated tubercle bearing 

 a great spine, around which are several small ones. There are a 

 great number of species, fossils from the jura, chalk, and tertiary 

 deposits, as also many living ones. 



C. Blumenbachii, Munst. — C. Buchii, Munst. — C. coronata, Goldf. — C. 

 cremdaris, Lam. — C. elegans, Munst. — C. Jlorigemma, Phil. (C. elongata, 

 Room.) — C. glandifera, Goldf. — C. marginata, Goldf. — C. maxima, Munst. 

 — C. monilifera, Goldf. — C. muricaia, Rcem. — C. nobilis, Munst. — C. pro- 

 pinqua, Munst. — C. Schmidelii, Munst. — C. spinulosa, Roem. — C. regalis, 

 Goldf. — C. clavigera, Koen. — C. corollaris, Mant. — C. cretosa, Mant. — C. 

 clunifera, Ag. — C. vesiculosa, Goldf. — C. limaria, Bronn. — C. discus, Bronn. 

 — C.rosaria, Bronn. — C. serraria, Bronn. — C. hystrix, Lam. — C. baculosa, 

 Lam. — C. tribuloides, Lam. — C. verticillata, Lam. — C. tubaria, Lam. — C. 

 bispinosa, Lam. — C. annulifera, Lam. — C. metularia, Lam. — C. stelhdifera, 

 Bory. — C. imperialis, Lam.-— C. granioides, Lam. — C. pistillaris, Lam. 



2. Diadema, Gray. {Cidarites, Lam.) — Shell more or less flattened ; 

 ambulacra large, converging uniformly towards the summit. The 



Ann. Nat, Hist, Vol.1. No. 4. June 1838. x 



