227 



As Mr. Donovan possessed a more perfect specimen of the fossil 

 remains of this animal, than I could procure, I requested and ob- 

 tained of him the following accurate description from the ticket 

 which accompanied his specimen. 



" The Tortoise Asterio Encrinus, an animal partaking of the nature 

 of marine crustaceous creatures. It is composed chiefly of sixteen 

 angulated pieces or plates, of which five pentagonal ones surround 

 the mouth, in the upper edge of each of which is a semicircular notch, 

 from which depends a jointed arm or tentacula, which is dichoto- 

 mous after the first two joints, and is probably again divided and sub- 

 divided towards its extremities. Those arms were, no doubt, designed 

 by nature to assist in taking its food: Immediately under these five 

 plates are five other hexagonal ones ; and below these, five more that 

 are pentagonal, and the bottom is terminated by a single pentagonal 

 plate. All the plates fit closely into each other in the same manner 

 as the scales of a tortoise, so that no interstices appear, and these are 

 radiated from the centre to the edges ; the upper plates with four 

 or five rays each, the rest with six rays each : from the sides of these 

 ridges proceed lesser ones, terminating at the edge, and giving them 

 a pennate appearance. The plate from which the branched arms 

 proceed, are not so much striated between the larger rays as the other. 

 In some plates, the striae are broken, and form a rugose surface. The 

 plates vary in their markings in different individuals, and even in the 

 same specimen, some are coarsely ridged, or rayed; some finely 

 ridged, or rather striated, and some are nearly smooth. The body 

 does not seem capable of extension. Found in a chalk-pit in Surry." 



Mr. Ingham Forster's Museum, O. 98 - 



Whilst attending to the forms, as well as to the different markings- 

 of the plates, of which this animal is composed, you will not fail to ob- 

 serve some similarity with those of the encrinite just examined, and 

 designated by the term Nave Encrinite. One material difference, 



