8 



LETTER II. 



JECHINITES ARRANGEMENT OF LESKE ADOPTED THE VARIOUS 



SPECIES OF THESE FOSSILS DESCRIBED ANOCYSTI, DIVIDED 



INTO CIDARES AND CLYPEI. 



1 HE next subjects of our inquiry are the fossil substances termed 

 Echinites, the mineralised remains of the echinus; an animal of a 

 roundish form, covered with a bony crust, approaching nearer to the 

 coverings of the crustaceous than to those of the testaceous animals, and 

 furnished with moveable spines ; the mouth being placed beneath. The 

 characters of many of these bodies are so remote from each other, as to 

 seem to point out the propriety of considering the whole as forming a 

 distinct order of vermes, thus marked out as different genera, possessing 

 other characters, which would well serve for the distinction of species. 



Many have endeavoured to bring the incongruous assemblage in the 

 Linnsean genus, echinus, into a more lucid and instructive arrangement. 

 To this work the labours of Muller, Phelsum, Bruguiere, and La- 

 marck, have much contributed : but to no one is more merit due, 'in 

 this respect, than to the industrious Leske, the ingenious commentator 

 on Klein's useful work. It is intended, in the following pages, chiefly 

 to be aided by the arrangement of Leske, who has also availed himself 

 of the labours of Phelsum and of Muller. 



Agreeable to this arrangement, the first class of these bodies which 

 we shall examine is that of the ANOCYSTI, the vent of which is in the 



