New Species of Devonian Fossils. 147 



Holopea planidorsata, n. sp. 



Plate IV, fig. 13 



Description: Shell small, of three or four whorls wound in a 

 moderate spire; apical angle about 90°. Base hemispherical, 

 with a very tiny umbilicus or none. Whorls flat and horizontal 

 on top, with the shoulder rather sharply rounded. The ambitus 

 is just below the shoulder, and from here to the axis of the base 

 the whorl is strongly and evenly convex. Each whorl rises about 

 three-fourths its height above the succeeding, and the sutures 

 are deep. The younger whorls' are more evenly rounded than 

 the last one. Aperture entire and vertical. Inner lip thin and 

 recurving so as to enclose a very narrow hollow axis, or to form 

 a columella. Surface marked by very fine and even lines of 

 growth that have a strong retral arch on the upper side of the 

 whorl, but are nearly straight and vertical from the ambitus to 

 the umbilicus. 



Dimensions: Height, 15 mm.; width, 15 mm.; height of aper- 

 ture, 8 mm. ; width of same, 9 mm. 



The flattened shoulder and deep suture of this species are 

 distinctive. 



Occurrence: Rockhouse shale, at Rockhouse, on Horse Creek, 

 Hardin County. 



Diaphorostoma quadrangulare, n. sp. 

 Plate IV, figs. 20, 21 

 Description: Shell low-spired, consisting of between three and 

 four gradually but rapidly expanding volutions. In cross-sec- 

 tion the whorls are rounded subquadrangular. The upper side 

 is very gently convex and horizontal, the outer side is almost 

 vertical and is marked by an undefined median slightly concave 

 zone. The base is as broad as the top and almost horizontal, 

 but a little more strongly convex than the top side of the whorl. 

 The four angles of the whorl are rather broadly rounded. The 

 aperture entire, subquadrangular, and slanting somewhat 

 obliquely backward below. Inner lip smooth. Base perforated 

 by a narrow umbilicus. Surface marked by fine lines of growth 

 and uneven coarser varices of growth which cross the whorl with 

 a gently sinuous course, being gently convex forward at the 

 center of the upper and outer sides, concave forward over the 



