Class VI. ECHINUS. 141 



nues, two of them shorter than the others ; the 

 (anus) vent is round, placed about midway 

 between the mouth and the margin, with four 

 pores at the top; color whitish; somewhat 

 concave beneath; often nearly circular, some- 

 times more ovate ; diameter not exceeding three 

 tenths of an inch. 



I have seen none of this delicate species till 

 after it had lost its spines, and have only found 

 it in Red Wharf sands in Anglesey. Tab. 

 xxxviii.^. I, 2. Jig. 3, much magnified. 



