319 



of a hogshead, in one cavity, of a sweetish taste, but accompanied 

 with a vitriolic, or iron-like twang*. 



Dr. Woodward, speaking of some specimens of enhydri, says-f, 

 " they were found, amongst many others, in sinking the wells in 

 Caen-Wood, whence that water, which we call the Hampstead water, 

 is derived. I was down only in one of the wells, which they were 

 then in digging ; but I saw several of these enhydri, with a pretty 

 many pyrites, amongst the earth that was flung forth .of the other 

 wells. They are of several sizes, from the bigness of a walnut, to 

 about two feet in breadth. They are generally of a compressed 

 shape ; and lessen, or grow thinner, towards the edge, or ambitus, 

 of them. Those that I saw, lay about fifteen or sixteen feet deep, 

 in a stratum of sandy clay. The surfaces of that stratum, and the 

 flats or larger plains of the enhydri, lay parallel and level: they 

 were all hollow, and usually divided into several cells ; but these 

 were uncertain, in their number, figure, and capacity. The parti- 

 tions of the cells were rarely very thick. The outer coat was in 

 some double, in others triple, and in a few quadruple; as consist- 

 ing of two, three, or four strong crusts, involving and carrying one 

 another. The cavities or cells were generally near full of an insipid 

 coagulum, or liquor, about the consistence of cream, though in 

 here and there one, it was a little thicker. Twas most commonly 

 of a greyish colour ; but in some few 'twas of a bluish, and in 

 others of a blackish hue." 



Whether it be believed, that these several bodies owe their exist- 

 ence to fire or water, it will, I conceive, be equally admitted, that 

 they have been formed in cavities, previously existing in the matrix, 

 in which they are contained. I suppose, then, that one of these 

 cavities becomes filled, by some small aperture, with a liquid hold- 



* The N tural History of Staffordshire, by Robt. Plott, LL. D. 1686. 



t ATI Attempt towards a Natural History of the Fossils of England, by J. Woodward, M. D. 



