412 Prof. F. M'Coy on the Classification of 



cheeks wider, and the border not being more than half the depth, 

 as well as being by no means so distinctly radiated. 



Common in the lower Silurian limestone of Golden Grove ; 

 the schists of Tre Gil ; and Caradoc sandstone of Alt y Anker, 

 Meifod ; also at Pen y Craig. A variety with a shorter shield, 

 the lobes of which are more spherical, perhaps from pressure, oc- 

 curs in the black Wenlock shale three miles north of Builth. 



(Col. University of Cambridge.) 



Harpidella (M'Coy), n. g. 



Gen. Char. Cephalic shield subtrigonal, surrounded by a thick, 

 narrow, flattened border ; sides nearly vertical, compressed ; 

 cheeks entirely surrounding the glabella in front, forming there 

 a narrow tumid border, widening backwards as they descend 

 into tumid, broad, triangular, nearly vertical wings, having 

 large prominent eyes near the middle of their posterior mar- 

 gin, and from them on each side an obscure impressed line 

 extends upwards and inwards to about the first third of the 

 glabella (perhaps indicating the eye-line) ; glabella very con- 

 vex, semielliptical, obtusely rounded in front, surrounded by 

 a strong defining sulcus ; two segmental furrows on each side, 

 the first very strong, curving, from about the middle of the 

 sides of the glabella, inwards and backwards into the neck- 

 furrow, so as to include a large tumid ovate lobe on each side ; 

 a little above this, the very short and faintly marked anterior 

 segmental furrow curves in the same direction ; surface granu- 

 lated. (Type of the genus Harpes ? megalops, M'Coy, Syn. 

 Sil. Fos. Irel. t. 4. f. 5.) 



The head alone of this genus is known, which differs from 

 Harpes (Gold.) in its small size, narrow unpunctured rim, ab- 

 sence of the ocular tubercle on the anterior part of the cheeks, 

 great size and basal position of the eyes, &c. 



(Fam. Lymnadiadce.) 



Ceratiocaris (M'Coy), n. g. 



Etym. Kepdnov, siliqua, and /caph, squilla. 



Gen. Char. Carapace bivalve, the dorsal line simply angulated 

 (? undivided), with a slight furrow beneath it on each side ; 

 sides semielliptical, much elongated from before backwards, 

 evenly convex, ventral margin gently 

 convex, posterior end abruptly trun- 

 cated obliquely ; on each side near the 

 anterior end considerably below the 

 hinge-line is an ocular (?) spot, some- Ceratiocaris. 



times raised and distinct, in some spe- a - The ocular spot. 



