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 

 sometimes 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. Echinanihus, 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. 



