KEPTILES ABUNDANT. 



73 



echimis, or sea-urchin, and the goniaster, which last is regarded 

 as a link between the echinus and star-fish. 



FIG. 49. 



Echinus mammillatus (recent). 

 FIG. 50. 



Goniaster equestris (recent) . 



Among the crustaceans of the oolite, a conspicuous place is 

 due to the limulus, or king-crab, of which several species 

 occur in this formation. This animal is remarkable as in its 

 embryotic state bearing a resemblance to the trilobite ; and 

 the appearance of the limulus at the time when the trilobite 

 vanishes (the carbonigenous era), is spoken of by a distin- 

 guished geologist as " one of those beautiful links in natural 

 history, of which the strata forming the earth's crust have 

 afforded so many proofs." 1 Here also we have, in the eryon, 

 an early example of the highest crustacean order (decapoda), 



1 Murchison, Geology of Russia. 



