New Species and Ne7v Shuctnial Parts of h'ossils. 85 



Cyclocystoidhs, sp. 



Plate I, Fig. I ^, fragment of superior side, showing part of the 

 ring, the outer rim, having manimillaryjcars, and below and 

 beyond this, plates from the other side ; on the interior of the 

 ring may be seen the commencement of the iiiternal rays, and 

 belo7V this the plates bclo7iging to the other side ; Fig. 14, 

 plates on the dorsal side of the sa?ne specimen; Fig. 15, the 

 same magnified tivo diameters. 



The ring is mineralized and cracked, so it does not show the 

 plates, and, therefore, the species to which this fragment 

 belongs can not be determined. Judging from the rim it 

 belongs to C. magnus, or an allied species. The plates on the 

 dorsal side, not only cover the internal disc, but they cover 

 the dor.sal side of the ring and rim and may be seen extend- 

 ing beyond even that. Probably, in a better preserved speci- 

 men, an outer rim of minute plates exists .beyond the rim of 

 mammillary elevations. The dorsal plates are so large that it 

 is remarkable that they have remained unnoticed until this 

 time. 



Found in the Hudson River Group, on the hills, in Cincin- 

 nati, h\ Mr. Faber. 



Agkl.vcrixus pileus? 

 IVate /, Fig. 10, the under side, sho7ci)ig part of the structure. 



We suppose the specimen before us is the under side of 

 Agelacrinus pileus, because of its depth, but it may be A. cin- 

 cinnatiensis. Probaby the lower side of each is constructed 

 substantially alike, as there is very little diflference between 

 their upper faces. We have no recollection of ever having 

 read a description of the under side of any specimen, in this 

 genus, except that given by Meek, in Ohio Pal., vol. 2, p. 55, 

 as follows : 



" The under side of each arm or ray is here seen to be com- 

 posed of a single series of quadrangular pieces, that are not 

 imbricating ; while the disc plates near the outer margin show, 

 on their inner surfaces, little parallel ridges, directed inward, 

 and apparently fitting into corresponding furrows in the lap- 

 ping edges of the contiguous pieces." 



