9 



but the openings are unknown. Column comparatively large com- 

 posed of thin plates and tapering as in Sfeleocysfites. Type J). 

 Wetherbyi. 



BELEMNOCYSTITES WETHERBYI, 11. sp. 



Plaie T, Fig. 4, dorsal side of a specimen with part of the column 

 attached; Fig. 5, dorsal side of another specimen with 

 column and part of the plates broken off ; Fig. 

 6, ventral side of same, part of the plates 

 only being distinguishable. 



In 1881 Professor A. G. Wetherby, in an article entitled "De- 

 scriptions of New Fossils from the Lower Silurian and Subcar- 

 boniferons Rocks of Kentucky," published in Jour. Cin. Soc. Nat. 

 Hist., vol. 4, p. 177, pi. Y, figs. 2 and 2a, called attention to a 

 "new genus and species" of cystideans, without attempting to give 

 it a name or determine its affinities. Fig. 4 is a reproduction of 

 his figure 2, which is, evidently, the dorsal side of the specimen. 

 He said of it: "The column is round and tapers rapidly. The 

 peculiar character of this anomalous fossil is the presence of a 

 single arm, originating between two large plates which form the 

 apex of the body on the (ventral) side. Seven plates of the arm 

 are shown. Near it, upon the left side, as shown in the figure, is 

 a small tubercle, evidently formed by valvular plates now silici- 

 fied so as to obscure their arrangement." Our specimen, as shown 

 in figures 5 and 6, is just like his, except the lower part is broken 

 away, and we have attempted to give a better view of the ventral 

 side than is shown in his figure 2a. We have given him the 

 honor of the specific name. 



Body compressed, convex on each side, within the marginal rim 

 of plates, outline subovoid, truncated at the base for the attach- 

 ment of a large column, which is composed of thin plait s and 

 tapers rapidly. 



There are nine plates in the marginal rim, not including the 

 two which abut upon the column. Five on one side and four on 

 the other. These plates are large and sutures distinct. The 

 sutures are exactly opposite each other on the two sides and are 

 plainly shown curving over the margin, which is thin and sharp. 

 This peculiar rim of plates increases in thickness on the ventral 



