65 



The arms are divided into three clusters, which are located 

 at the angles of the summit. There are three arm openings at 

 one of the angles and two at each of the others. The three- 

 armed angle is opposite the mouth. There are, therefore, seven 

 arms in this species. The plate over each arm opening bears 

 a node and there is a small plate between each of the arm 

 openings. 



This species is distinguished by its general form from all 

 others. The triangular summit is peculiar and the arrange- 

 ment of the seven arms at the angles is different from that in 

 any other described species. 



Found by Mrs. J. M. Milligan, in whose honor we have pro- 

 posed the specific name, in the Niagara Group, in Decatur 

 county, Tennessee, and the specimen illustrated is now in her 

 collection. The species is also represented in the collection of 

 each of the authors, though the type is the best preserved and 

 shows the sutures between the plates better than our speci- 

 mens do. 



CARYOCRINUS HAMMELLI, n. Sp. 



Plate V, Fig. 5, azygous side view, Fig. 6, summit 



Species large, subelliptical in outline, the angular convexity, 

 at the middle of each plate, in the second range, gives an 

 hexagonal outline to the middle part of the body. The summit 

 is irregularly subcircular or suboctagonal. Ridges radiate from 

 the center of each plate to the angles, in the form of coalescing 

 nodes, except on the basal plates, where the ridges run from 

 the superior angles toward the point of columnar attachment. 

 There is a single or a double row of pores accompanying these 

 ridges and there are nodes and pores on other parts of the 

 plates. 



Three of the basal plates are about equal in size, but the 

 other one is nearly twice as large as either of them. The large 

 plate is hexagonal in outline, and the others are quadrangular. 

 They form an hexagonal cup about one-third the length of the 

 body. The six plates in the second range are of unequal size, 

 and the larger ones follow the smaller basal plates so that the 

 symmetry of the body is restored; two are pentagonal, two 

 hexagonal, and two heptagonal. They are longer than the 

 plates in either of the other ranges. There are nine plates in 

 —9 



