159 



OUR COMMON BRITISH FOSSILS. 



three miles, and it is known by the name of Calymne 

 relicta. The bottom of the Atlantic is remarkable for 

 a number of creatures living there which are allied to 

 those found in the fossil state in the Chalk formation^ 

 The family of sea-urchins called Pourtalesia is of this 

 character, for it is allied to the extinct Ananchytes in 

 many respects. But perhaps the most remarkable 

 living Atlantic sea-urchin is Salenia varispina^ dredged 

 off Cape St. Vincent at a depth of nearly two miles. 

 A few years ago this genus was believed to have beeri 

 extinct for ages, for it was not found outside the 



Fig. XQ.^.— Echinus 

 gran-ulosus. 



Fig. Ti-j.—Saknia 

 j>ersonata. 



Chalk, unless we except the Acrosalenia of the 

 London Clay, at Sheppey. Now it has turned up in 

 the living state in the Atlantic. Salenia is common 

 in the Chalk near Norwich, and internal flint casts are 

 also found there so abundantly that they go by the 

 name of " pick-cheeses " — " pick-cheese " being the 

 name given to the ripened seed-vessels of the common 

 mallow, which the flint casts of Salenia very closely 

 resemble. Internal flint casts of Ananchytes, or 

 ** fairy-loaves," are abundant wherever the Upper 

 Chalk crops out, and they are often remarkable for 



