137 



17. G. umbrella. — Is questioned as being clypeus sinuatus 

 of Klein, with which the description agrees ; but Lamarck 

 has not adverted to the vent in clypeus being on the upper 

 surface. Fossil. 



1 8. G, excentricus. — Ovate, convexly gibbous ; the vertex 

 excentrical, from which proceed four ambulacra ; the lower 

 side sulcated with five grooves. 



This curious and irregular formed fossil is described as 

 being as large as the preceding. Its habitat is not mentioned. 



19. G, subuculus. — Discoidal; vertex subrotund; base 

 rather concave; the whole surface of the areas set with 

 minute rings ; the ambulacra biporous ; the mouth small 

 and circular ; the vent even, minute, and circular ; the vertex 

 sornetimes scutellated in those specimens in which the shell 

 remains. Fossil. 



Echinites subuculus of Leske, figured by Klein, Tab. xiv. 

 1. m. n. o. Fossil. 



Genus VIII. Clypeaster. — Oval, or elliptical ; sub- 

 angular ; somewhat raised and gibbous in the centre ; the 

 margin thick and rounded ; the under side concave at the 

 centre ; the mouth, armed with six bony pieces, is beneath, 

 and central ; the vent beneath, and in or near to the margin ; 

 the ambulacra, on the upper surface, in a pentapetalous 

 form. — PL ii. fig. 2. 



Synon. Scutum, Klein. Echinanthus, Leske. 



Sp. 1. Cl.humilis. — Ovate; margin winding ; ambulacra 

 with two rows of pores connected by small transverse 

 grooves, and so disposed as to form the sides of five peta- 

 loidal figures ; the larger areas are disposed around ; the 

 smaller ones circumscribed by the ambulacra, and somewhat 

 raised; the surface covered by granular tubercles, set in 

 rings, with numerous smaller grains interposed; the base 

 flat towards the margin, and concave in the middle ; the 

 mouth deeply seated in the centre, of an obtuse pentagonal 

 form ; the vent transversely oval. Recent and fossil. 



T. 



