PLATE XVIII. 



Halonia regularis (No. 38). 



This drawing represents tlie outside of a specimen, partly coated with its epidermis 

 (converted into coal), and partly bared. Thus are seen both the areolae and the tubercles, 

 according to the condition in which the outside of the specimen is exposed. From the 

 Peel Delph, near Bolton-le-Moors. Natural size. 



