1885.] NATURAL SCIENCES OF PHILADELPHIA. , 333 



Beneath the interaxillary plate, the figure indicates the presence 

 of two plates, separated laterally, which, combined, have the form 

 and position of a bifurcating plate. That there is a mistake in 

 the figure with regard to these plates, seems to us beyond ques- 

 tion. There is evidently but one plate in the specimen, and this 

 represents a primary radial, while the two plates at each side of 

 it, as in the succeeding ring, are interradials. The figures do not 

 extend beyond this ring, all lower plates being evidently hidden 

 from view by the large column, and hence the exact number of 

 primary radials and basals is not known, but this was undoubtedly 

 similar to that of allied genera, and not so abnormal as given by 

 Angelin. 



If it has three primary radials and four basals, which seems to 

 us most probable, and at the same time a distinct anal interra- 

 dius, we should not hesitate to place Polypeltes as a synonym 

 under Abacocrinus, while under the same conditions, but with 

 only three basals, it agrees with Megistocrinus. However, should 

 it be proved that the posterior interradius has no additional 

 plates, but is constructed like that of the four other sides, Poly- 

 peltes should be placed under Corymbocrinus. Only a variation 

 in the number of primary radials, if our interpretation is correct, 

 will warrant a generic separation, but in this case the name should 

 be changed, as it becomes meaningless. 



We suggest that in Polypeltes (?) the basals and the greater 

 part of the primary radials form a deep concavity, which, to a 

 large extent, is filled by the column, as in the case of Corymbo- 

 crinus, Megistocrinus and Eucalyptocrinus. We found a very 

 similar case in Megistocrinus concavus Wachsmuth, from Alpena, 

 Michigan, in which the basals and first radials form the lateral 

 walls of a deep concavity, and are entirely hidden from view. 

 The second radials are partly exposed, and form, with adjoining 

 pieces, a ring of twelve very even, strongly nodose plates, which 

 consist of five radials, four regular interradials, and three anal 

 plates. Nobody would suspect one of these specimens to be a 

 Megistocrinus, unless he obtained access to the deep funnel which 

 contains the missing plates. 



We deem it unnecessary to give a special diagnosis of Poly- 

 peltes, as we think it will eventually be placed under Abacocrinus 

 or Corymbocrinus. It has the same long, branching arms, com- 

 posed of two series of narrow interlocking pieces, and, as in that 



