Silurian Fossils. 33 



This species is distinguished from Klocdcnia susscxensis, 

 Weller, chiefly by the position of the middle lobe, which is 

 more remote from the dorsal margin. The steep, slightly 

 concave marginal area along the ventral and anterior mar- 

 gins is an additional feature. 



Illaexus depressus, Focrstc. 



An excellently preserved specimen, closely resembling fig- 

 ure 2 on plate 26 of volume 7 of the Geology of Ohio, occur- 

 red at the Spring on Big Salt Lick creek, one mile south of 

 Glen Springs, in Lewis county, Kentucky, and a similar speci- 

 men was found in the same county, northwest of Martins, in 

 both cases in the West Union limestone. Compared with 

 lUaenus aincricainis^ Whitfield, this pygidium is broader an- 

 teriorly, more triangulate, and hence more angularly rounded 

 posteriorly. Compared with lUaenus triloba, \\'eller, the an- 

 terolateral angles are less truncated and the depression along 

 the border is less conspicuous and disappears before reaching 

 the anterior margin. 



Calymexe clixtoxi, l^anuxcm. 

 Plate I, Fig. 6. 



Cephalon short and broad, with the width about three and 

 a half times the length. Compared with Calymene iiiagarcti- 

 sis, the glabella is considerably flatter, shorter, and broader, 

 especially posteriorly. In one specimen the width across the 

 posterior lateral lobes is 11 mm. ; across the middle pair, 7.4 

 mm. ; across the anterior pair, 7 mm. ; and across the frontal 

 lobe the width is slightly more than 7 mm., while the length 

 of the glabella anterior to the middle of the occipital furrow 

 is only 7 mm. The posterior lateral lobes are large and 

 rather triangular in form, owing to the diagonal course taken 

 by the furrows separating these lobes from the middle pair. 

 Along the median line of the glabella these furrows arc 

 scarcely 2 mm. apart. The other furrows are short and ap- 

 proximately at right angles to the median line of the glabella. 



33 



