L. Agassiz on the Echinodermata. 443 



A. prisca, Ag. (Ophiura prise, Munst.) 



5. Aspidura, Ag. — A star of ten plates covers the upper surface 

 of the disc, while the rays, which are proportionally large, are sur- 

 rounded by imbricate scales. One fossil species. 



A. loricata, Ag. (Ophiura loric, Goldf.) 



6. Trichaster, Ag. (Euryale, Auct.) — Rays furcate at their ex- 

 tremity. 



T. palmifer, Ag. (Euryale palmifer, Lam.) 



7. Euryale, Lam. (Astrophyton, Link. — Gorgono-cephalus, Shaw.) 

 — Disc pentagonal ; rays branched and sub-branched from their base. 



E. verrucosum, Lam. — E. costatum, Lam. — E. asperum, Lam. — E. muri- 

 catum, Lam. — E. mediterraacum, Risso. (This last species does certainly 

 exist in the Mediterranean ; I have seen several specimens collected in the 

 bay of Naples by Dr. Buckland. I make this observation because the exist- 

 ence of this species has "quite recently been placed in doubt, although Ron- 

 delet mentions it.) 



III. The Crino'idea, notwithstanding their starlike form and their 

 great external resemblance to the Asterice, constitute however a distinct 

 family, characterized by the presence of two separate orifices to the 

 intestinal canal, although very near to each other. These orifices 

 are by no means easily distinguished among the rays which surround 

 them, especially in the fossil species. The greatest part of the species 

 are pediculate, i. e. carried on a foot-stalk adhering to the centre of 

 the region, which, in the star fish, we considered as the middle of the 

 dorsal surface. 



1. Comatula, Lam. (Astroconm, De Bl. — Decameros, Link. — 

 Antedon, Frem. — Alecto, Leach.) — Disc pentagonal, arched at its 

 upper surface, which bears several series of simple and articulated 

 rays ; rays of the disc bifurcate, beginning however with two simple 

 pieces. The edges of the rays are pinnate ; mouth central, sunk ; 

 anus between the mouth and the border of the disc, obliquely promi- 

 nent. Animal entirely free. 



C. mediterranean Lam., &c. 



2. Comaster, Ag. (Comatula, Auct.) — This genus has the same 

 organization as the preceding, but the arms are ramified instead of 

 being simply furcate. 



C. multiradiatus, Ag. (Comat. mult., Lam.) 



3. Pterocoma, Ag. — Rays pinnate, developed to such a degree 



and so deeply bifurcate, that there appears to be no disc ; body free. 



A fossil species. 



Pt.pinnata, Ag. (Comatula pinn., Goldf.) 



4. Saccocoma, Ag. — The disc presents the form of a rounded 



