ECHINODERMATA. 155 



Echinolampas GRAY, AGASS. Ambulacra circumseript, very wide 

 at the summit, narrower towards the margin, not conjoined. Disc 

 submarginate forwards. Genital pores four. 



Sp. Clypeaster eccentricus, Echinolampas Kleinii BRONN Leth. geogn. Tab. 

 XXXVI. fig. 10 : fossil from the tertiary formations, &c. 



Scutella LAM. Body flattened, with margin thin, sub-acute. 



Ambulacra short, circumscript, resembling a pentapetalous flower. 



Anus inferior between the mouth and the margin. Genital pores 



four or five. 



From this genus AGASSIZ at first separated the sub-genus Echin- 

 arachnius (Prodrome d'une Monogr. des Radiares, &c.,) afterwards 

 he divided the genus Scutella of LAMARCK into thirteen genera 

 (Monogr. d'Echinod., 2e Livrais. les Scutelles) ; Rotula KLEIN, 

 AGASS., Euna AGASS., Mellita KLEIN, Encope AGASS., Lobophora 

 AGASS., Amphiope AGASS., Scutella AGASS., Echinarachnius "V. 

 PHELS., Arachnoides KLEIN, Scutellina AGASS., Laganum KLEIN, 

 Echinocyamus V. PHELS., Moulinia AGASS. 



Sp. Scutella sexforis LAM., Mellita kexapora AGASS., GUERIN Iconogr. Zooph. 

 PI. 3, fig. 4, Cuv. R. Ani. ed. ill., Zooph. PI. 15, fig. i. AGASS. Monogr. 

 Livr. 2, PI. iv. fig. 4 7, PI. iv a . fig. n, 12 ; from the shores of the Mo- 

 lucca Islands, &c. Scutella dentata LAM., Rotula Rumphii KLEIN, AGASS., 

 KDMPH. Ami. Rariteitlc. Tab. xiv. fig. i, &c. (LINN2EUS comprehended all 

 the species known to him under the name of Echinus orbicularis). Except 

 a very small number from the chalk-formation, all the fossil species of this 

 genus are from the tertiary formations. 



** Anus superior central, opposite to the mouth. Test regular. 

 Ambulacra, perfect. Genital pores, Jive. (Cidaridea GRAY, AGASS.) 



Echinus LAM. (spec, of genus Echinus L.) Ambulacra wider 

 towards the middle of the test, divergent, contracted at the summit 

 and towards the mouth. Spines placed upon imperforate tubercles, 

 sometimes very long. 



Sp. Echinus lividus LAM. (Echin. sexatilis TIEDEM. 1. 1.), VALENTIN in AGASS. 

 Monogr. d'Echinod., Liv. 4, PI. i, EASTER NatuurTc. Uitsp. i. Tab. xi. 

 fig. i 8, FORBES Brit. Starf. p. 167. In the Mediterranean and North 

 Sea, &c. For the synonomy of the European species of Echinus comp. 

 AGASSIZ in the preface to the fourth number of his Monographies. 



Arbacia GRAY, AGASS., Echinometra BREIJN, GRAY, AGASS. 

 Sp. Echinus mamillatus L., Echinometra mamillata. RUMPH. Amb. RariteitJc. 



Tab. xni. fig. i, 2, Cuv. R. Ani. edit, illustr., Zooph. PI. xm. fig. i, East 



Indian Sea, &c. 



Salenia GRAY, AGASS. (Goniopygus, Peltaster, Gfoniophorus AGASS.) 

 Comp. AGASSIZ, Monogr. d'Echinod. Livr. r. 



