301 L. Agassiz on tin* Eckinodermata, 



(Echinon. scut., Munst.)- — /•'. tvffblcietuis, Leach. — F. cratiioluru, Linn., 

 (iiiirl. — F. ovulum, Lain. 



9. Echinoneus, A', rials, and Lam. (Eckinanaus, Keen. — Echi~ 

 noconus, Breyn.) — Disc oval, more or less, flattened ; ambulacra con- 

 verging uniformly towards the summit; anus between tbe mouth 

 and posterior margin. All the species are living. 



E. cyclostomut, Lain. — 11. semilunaris, Lam. — E. gibbosus, Lam. 



10. Echinolampas, Gray. (Echinanlhus, Leske. — Clypeaster and 

 Galerites, Lam.) — Disc oval or circular ; front margin more or less 

 sloped ; ambulacra very large at the summit, where they form a 

 star, the rays of which touch one another, but which gradually be- 

 come more narrow towards the periphery ; anus marginal, inferior. 

 There arc some fossil species from the jura, the chalk, and tertiary 

 deposits, and one living. 



E.prutagonalis, Ag. (Clyp. pen tag., Phil.) — E.fornicafus, Ag.(Clyp.forn., 

 Goldf.) — E. globosus, Ag. (Gal. glob., Defr.) — E. Kcenigii, Or. — E. Les- 

 kei, Ag. (Clyp. Lesk., Goldf.) — E. Montmollini, Ag. — E. productas, Ag. — 

 E. minor, Ag. — E. affinis, Ag. (Clyp. aff., Goldf.) — E. Bonei, Ag. (Clyp. 

 Bouci, Munst.) — E. Erongniarli, Ag. (Clyp. Brongn., Munst.) — E. conoideus, 

 Ag. (Clyp. conoid., Goldf.) — E. Cuvieri, Ag. (Clyp. Cuv., Munst.) — E. el- 

 l/pticus, Ag. (Clyp. ellipt., Munst.) — E. hemispliaricus, Ag. (Clyp. hemisph., 

 Lam.) — E. Kleinii, Ag. (Clyp. Klein., Goldf.) — E. Linkii, Ag. (Clyp. Link., 

 Goldf.) — E. poliius, Ag. (Clyp. poll., Lam.) — E. stelliferus, Ag. (Clyp. stel- 

 lif., Lam.) — E. subcylindricus, Ag. (Clyp. subcyl., Munst.) — E. trilobus, Ag. 

 (Clyp. tril., Defr.) — E. orient alls, Gr. 



11. Clypeaster, Lam. (Echinanlhus, Breyn. and Gr.) — Echino- 

 dorum and EcJiino discus, V. Phils. — {Lagana, Gr. and De Bl.) — Disc 

 oval or subpentangular ; ambulacra forming at the summit a large 

 star, the rays of which are rounded at their extremity ; anus inferior 

 and marginal. The internal cavity is divided into chambers by ver- 

 tical pillars. The shell is very thick. There are several fossil spe- 

 cies from the tertiary deposits, and some living. 



CI. marginatus, Lam. — CI. altus, Lam. — CI. Gaymardi, Al. Br. — CI. Ri- 

 chardi, Desm. — CI. rosaceus, Lam. — CI. subdepressus, Ag. (Echinanthus 

 subdepr., Gr.) — CI. a?nbigenus, De Bl. — CI. scutiformis, Lam. 



12. Echinarachnius, Leske and Gr. (Arachnoides, Kl. — Echino- 

 discus and Lagana, De Bl. — Scutella, Lam.) — Disc circular or sub- 

 angular ; ambulacra as in Clypeaster, from which this genus espe- 

 cially differs by the much flattened form of the shell, and by its thin 

 margins ; anus marginal. There is one fossil species from the ter- 

 tiary beds, and several living. 



E. lenticularis, Gr. — E. placenta, Gr. (Scut, plac, Lam.) — E. Parma, Gr. 



