91 



Tbe disposition of these striae is as follows ; from the centre of each plate a ridge 

 proceeds to each sido of the polygon formed by it, bisecting each of the trian- 

 gular areas into which it may be resolved ; all the other striae contained hi each 

 of these areas are parallel to this first. (See fig. 1.) The configuration of the 

 contiguous plates being similar and adapted to each other, the markings proceed 

 over them in the same direction, thus producing a series of triangular striae, 

 arranged in such a manner that the ramifications from three contiguous plates 

 contribute to compose a single triangle. This disposition, which is common to 

 this and nearly all the following genera, will be better understood by an inspec- 

 tion of the plate, than from any verbal description. These rugged ridges ap- 

 pear to have resulted from the ramifying structure and contraction of muscles 

 adhering to the centre of each plate, where a rough and granular surface indi- 

 cates the points of their attachment, and thence acting partly towards the arms 

 to produce their motion, and partly towards the pelvis and column. 



The fibres at the base of this animal are frequently found entangled in the 

 branches of a coral, which I have called in my manuscript catalogue Hexapora 

 Cyathocrinoidea. 



It is this species whose superior portion and the markings ofits plates bear 

 great resemblance to the Marsupite (a name proposed by GIDEON MAMTELL, 

 Esq. of Lewes, in his manuscript account of the Southdown fossils), or Tor- 

 toise Encrinite of Mr. PAKKINSON, which animal forms the approximating 

 genus or intermediate link between this family and the genus Euriale of 

 LAMARCK. 



