1879.] NATURAL SCIENCES OP PHILADELPHIA. 363 



This has been already seen as to Poteriocrinus and Eupachy- 

 crinus, and will be still further proved in Stemmatocrinus, 

 which we consider to be the Russian representative of the 

 American genus Erisocrinus, although we are obliged to separate 

 them subgenerically. Trautschold describes his genus Stemmato- 

 crinus with a single subbasal plate, while in Erisocrinus the 

 pelvis is distinct^ divided into five pieces. We also observe a 

 difference in the construction of the arms, which in the former 

 are composed of a double series of interlocking plates, while in 

 the two species of Erisocrinus, in which the arms have been 

 found, they are composed of single transverse plates. Both spe- 

 cies, however, are from the Burlington limestone, and are very 

 small, and it is extremely probable, from analogy with contempo- 

 raries, that the arms in the species from the Coal measures, where 

 the genus flourished more abundantly, were, as in Stemmatocri- 

 nus, composed of interlocking pieces, and that the Burlington 

 species represent the young form. This would make the differ- 

 ence in the underbasals the only visible distinction. 



Meek & Worthen, after publishing the description of Erisocri- 

 nus, were led by its similarity to a genus described by De Koninek 

 under the name Philocrinus, from the Subcarboniferous rocks of 

 India, to believe it identical therewith, and ranged their species 

 under it accordingly. Later comparisons, however, led them to 

 reconsider this. They assert that if Philocrinus has no subradial 

 plates, then the two genera are clearly distinct; but, if small 

 plates should be discovered within the plates now called basals, 

 they are probably identical. We have never seen specimens, nor 

 even De Koninck's description of Philocrinus, and are unable to 

 express any opinion in the matter. 



Generic Diagnosis. Calyx saucer- to cup-shaped ; symmetry 

 strictly erpiilateral. General aspect similar to that of the two 

 preceding genera. 



Underbasals very small, forming a pentagonal, flattened, or con- 

 cave disc or low cup. Basals large, uniformly hexagonal. Radials 

 considerably larger than the basals, pentagonal, much wider than 

 high, upper sides straight. There being no anals, the plates of 

 each order or of each successive ring are of equal size and like 

 form, and alternate regularly with those of successive rows. Bra- 

 chials one by five, similar in form to the radials, but the lower 

 margins are straight and the upper obtusely angular for the sup- 



