15 



a large part of the truncated side showing the curving and termi- 

 nating ends of the arms. One of the other specimens shows part 

 of the interlocking arm plates and the other shows the covering 

 of the arm furrows almost complete. Whether there was a gaping 

 of the arm plates at the ends of the rays or not is not deter- 

 mined, but it is quite probable that they did, as such is fre- 

 quently found to be the case in Hemicystites. 



Found in the Trenton Group, in Mercer county, Kentucky, 

 and now in the collection of Wm. F. E. Gurley. 



FAMILY AGELACKINID.E. 



AGELACRINUS LEGRANDENSIS, 11. sp. 



Plate III, Fig. 13, tivo specimens, natural size, the smaller one 

 not as well preserved as the larger one; Fig. 14, same mag. 

 nified two diameters. 



The species in this genus seem to vary greatly in size, and we 

 have no doubt the two specimens illustrated belong to the same 

 species though the smaller one is not so well preserved as the 

 larger and may not furnish all the evidence necessary to warrant 

 a satisfactory conclusion in this respect. It is also quite probable 

 that the larger specimen does not reach the maximum size of the 

 species. 



The body is circular and only slightly convex. The outer rim 

 is composed of numerous small, squamiform, imbricating plates, 

 those upon the outer margin of it are so minute as to be almost 

 granular. The plates of the disc within the outer rim are also 

 squamiform and imbricating and somewhat larger than any of the 

 plates in the outer rim. There are only four arms, three of them 

 curve slightly to the right and one to the left. The arms are 

 slender and each consists of an angular ridge, composed of inter- 

 locking plates, and terminates after curving slightly on the inside 

 of the outer rim. The central part from which the arms radiate 

 is more convex than any other part of the body, but the plates 

 are so small that no peculiar structure is discernable.' The 

 specimens are somewhat injured in the region of the aperture 

 and apparently it is not at the center between the sinistral and 

 dextral arms, but between that point and the central elevation. 



