82 



THALAMOCUINUS OVATUS, n. sp. 



Pla'e V, Fig. 29, side view; Fig. 30, nzygous side; Fig. 31, sum- 

 mit view without the vault, magnified two diameters. 



Body small, oval or pear-shaped, greatest diameter at the 

 upper thii-d; length one third more than the diameter; surface 

 smooth. 



The five basal i)lates are of equal size and about one third 

 the length of the body. They are excavated below api)arently 

 for the attachment of a column, but the columnar canal is too 

 minute to be seen except with a strong magnifier and even then 

 it looks like a very minute, round orifice. The second series 

 of plates are subradial in position and alternate with the basals. 

 They constitute a little more than half the length of the body; 

 four of them are hexagonal and one is hejitagonal. The jilates 

 in the third range are short and five of them alternate with 

 the subradials. while one of them truncates the heptagonal 

 plate at the top, on the azygous side. The short plates form- 

 ing this circle are beveled toward the interior at the top, and 

 present an appearance much like Zophocrinns, when the vault 

 is removed in that genus, which indicates a similarity in the 

 vaults of the two genera. 



Pound by Mrs. J. M. Milligan, in the Niagara Orouj), in 

 Decatur county, Tennessee, and now in her collection. TJiere 

 are three specimens, one is smaller than the specimen illustrat- 

 ed, and another is more than twice as large, so that the nat- 

 ural size of it is as large as the illustrations. 



THALAMOCKINUS CYLINDRICUS, U. Sp. 



Plate V, Fig. 32. side view of two ranges of plates; Fig. 33, 

 summit view of second range, magnfied two diameters. 



Body small, subcylindrical iyv somewhat fusiform. Length 

 more than twice the diameter. Surface smooth. Sutures very 

 distinct and slightly beveled. 



Basals of equal size and having a length equal to tlie diam- 

 eter of the cup. Truncated below, and under an ordinary mag- 

 nifier no columnar canal is visible, thougli tju^re is a cicatrix 

 for some kind of attachment. Tlie second circle of plates al- 

 ternate with the ba.sals and form a small cylinder having a 

 length fully equal to the diametor. The thick ])lates may be 



