OF DENISON UNIVERSITY. 
I2I 
rug^ which striate the surface are more or less radial at the mouth of 
the pits but as they descend the elevation they rapidly take a common! 
direction and become quite parallel and more or less wavy between 
the elevations. The direction of the striae then is transverse to the 
direction in which the elevations are said to be more readily referable 
to series. This arrangement is very common in the genus Smithia of 
Edwards and Haine, a subgenus of Phillipsastma, D’Orbigny. 
The specimen referred to this species by Mr. William J. Davis^ 
(Kentucky Fossil Corals, PI. 123, Fig. i,) has not the slightest resem- 
blance either to the type or to the Onio specimen here under consid- 
eration ; it belongs rather to that smaller variety of S. pentagonus which 
is usually regarded as typical of the species. S. incertus, Davis of the 
same plate is a good medium sized specimen of the same species. 
S. pentagonus. Fig. 3, of PI. 121, is a similar form with a slightly less 
distinct margin around the pits in the centre of the calyces. S. siri- 
atus. Fig. I, of PI. 122, represents one of the larger varieties. A form 
slightly less in size, with more defined margins about the pits, is fig- 
ured by Rominger, Fossil Corals, PL 48, Fig. r. His figure 2 ot the 
same plate represents one of the smaller forms. The species is ex- 
tremely variable both in the size of the calyces, and in the fineness of 
their radial striations. Variation is however the normal condition of 
species of wide geographical distribution. 
S' 
Sph^rexochus mirus, Beyrich. 
{Plate XIII, Fig. 6 .) 
Since Hall, in the GeoL Rep. of Wisconsin. 1862, separated Sp^, 
Romingeri from Sph. mirus, on account of distinctions presented by 
the pygidia at that time associated with undoubted glabellas of a spe- 
cies of Sphmrexochus, it has been the fashion of American paleontolo- 
gists to refer all American specimens to Hall’s species. To show that 
this is probably incorrect, a description of the glabella of a specimen 
obtained in the Guelph at Cedarville, Ohio, is appended, which will 
be seen to agree even in the minutest details with the European forms 
referred to Beyrich’s species. 
Glabella almost hemispherical, slightly broader than long; two* 
small lobes cut off a part of each side of the glabella at the occipital 
