April, 1U17J Siliiriiui fossils from Ohio 203 



species of Calostylis have been described also from the Silurian 

 of Great Britain. Of these, Calostylis lindstromi, Nicholson and 

 Etheridge, occurs near Girvan, in Scotland, and Calostylis (?) 

 andersoni, Nicholson and Lydekker, in Shropshire, England. 



Calostylis belongs to an increasing number of peculiar genera 

 whose distribution suggests a former connection of American 

 epicontinental seas during Silurian times with those of the 

 Baltic area, and with Great Britain. 



Calostylis belongs to the Tetracoralla. This relationship is 

 more apparent in Calostylis parviila, here described, than in 

 the type species, owing to the simpler construction of the septa. 

 In Calostylis denticulata the septa of the older specimens tend 

 to have a spongy structure. In Calostylis parvula the pinnate 

 arrangement of the septa, diagnostic of the Tetracoralla, fre- 

 quently is distinct. (The Relation of the Tetracoralla to the 

 Hexacoralla, W. I.Robinson, 1917. Trans. Connecticut Acad., 

 p. 173.) 



Holocystites greenvillensis, sp. nov. Plate IX, Figs. 3A, B, C; 



Plate X, Fig. 8. 



Three specimens, none of which preserves either the base or the 

 summit; each retaining five horizontal rows of plates, each row con- 

 sisting of eight plates. In each specimen the third horizontal row is 

 located at mid-length, and forms the widest part of the theca. All of 

 the plates, as far as retained, are hexagonal in outline, excepting possibly 

 the uppermost series, which may have been pentagonal. At one side 

 of the upper end of each of these specimens there is evidence of a pro- 

 tuberance which is regarded as locating the anal opening. Orienting 

 the specimens in such a manner as to place this protuberance at the 

 rear, it is noticed that the plates along the middle part of the right 

 side of the theca (Figs. 3 A, B) are narrower, while those on the left 

 side (Fig. 3 C) are wider than the remainder. The thickness of the plates 

 is about half a millimeter. The surface of the plates is distinctly and 

 irregularh- granulose, the larger granules equalling about three-eights 

 of a millimeter in width. 



Among described species, Holocystites greenvillensis resem- 

 bles most closely the type of Holocystites abnormis, Hall (Twen- 

 tieth Annual Report, State Cabinet of Natural History, New 

 York, 1868, PI. 12, Fig. 7), however, the plates of the upper 

 two rows are very much narrower, especially on the right side 

 of the theca. Moreover, the general outline is more fusiform, 

 and the outline near the anal protuberance tends to be more or 

 less distinctly concave. In addition, the size is much smaller. 



