114 



these is the degree of agreement of the fossil remains with 

 the correspondent parts of the existing animals. But to 

 make this comparison, it is obvious that knowledge must be 

 obtained respecting those genera and species which have 

 been already discovered, either in their recent or fossil 

 states. To communicate this knowledge in the most correct 

 and impressive manner, different systematic arrangements 

 of these animals have been formed. 



Among the earliest attempts of this kind was that of 

 Dr. Woodward, in his catalogue of the foreign fossils in his 

 collection : a sketch of it is given here, not only as serving 

 to show the state of the science at that period, but as likely 

 to be useful for reference, since many of our early writers 

 on these subjects adopted the nomenclature which Dr. 

 Woodward had employed. 



Marine Echini. 



Part I. Those having two openings and very small tubercles on 

 the surface are called spatagi. 



Sect. I. Those having a remarkable groove at one side, cordiformes. 



Art. 1. With the openings at the sides, one under the groove, the 

 other at the opposite side. 



2. Cordiform spatagi, with one opening in the middle of the 

 base, the other in the groove. 



Sect. II. Spatagi, having no lateral groove, and with both openings 

 in the base of the shell. 



Art. 1. With one opening in the edge of the base, and the other 

 near to the opposite margin, called galeati. 



2. Spatagi, with one opening in the centre of the base, the 

 other in the margin. 



Divis. 1. With porous lines extending from the vertex to the 

 margin. 



Member 1 . Of a conoidal figure, or pileati. 



2. Of a compressed form, or dischoides. 



