INVERTEBRATES. 89 



POTERlorUl.NTS XODOHASA US. (sp. UOV.) 

 PL XII, Figs. 3-3a, and PI. XIII, Pig. 6. 



Calyx short, forming- a broad shallow cup below the brachial 

 series. Fnder basals visible around the column where they form 

 a small five-rayed star. Base depressed, basals prominent, and 

 projecting- below so as to form short transverse nodes. Radials 

 short, twice- as wide as long, pentagonal, and truncated squarely 

 across their upper margins. 



Brachials one to each ray. pentagonal, rather larger than the 

 radials. wider than long and supporting on their upper angles 

 the first arm plates. 



On the left antero-lateral ray. both divisions bifurcate again, 

 one division on the second, and the other on the fifth plate, 

 beyond which they appear to be simple to their extremities. 



Anal plates five visible, arranged as is usual in this genus. 



Column composed of thin pieces, and pentagonal where it 

 joins the body. 



Position and locality: St. Louis limestone, Monroe county, 

 Illinois. 



Collector, Henry Tolbot, Esq. 



No. iTtTT of the Illinois State Museum. 



PoTKIUOCRIXrS BUFFALOEXSIS. (sp. 1IOV.) 

 PL XII, Fig. 1. 



Calyx small, obconic below the summit of the radial plates. 

 or about once and a half as wide as high. Basals small, 

 pointed above, forming a low pentagonal cup. 



Badials two on each of the two rays visible, the first pentagonal 

 wider than high : the second quadrangular, and about twice as 

 wide as high. 



Brachials pentagonal, wider than high, pointed above, and 

 supporting on their upper sloping sides the first arm phn 



Arm two to each of the rays visible, composed of rather stout 

 joints that are longer than wide, and project slightly at their 

 upi>er inner margins where they support stout pinnul 



Anal series unknown. 

 11 



