EARLY DEVONIC HISTORY OF NEW YORK AND EASTERN NORTH AMERICA 203 



surface at the sides of the sinus is broad and Mat except about the margins 

 where it is more abrupt. 



Surface radii fine, rounded, numerous and subequal ; cardinal area 

 moderately high and curved downward at the sides. On the interior the 

 delthyrium is relatively broad and has encroached upon the beak, the pedicle 

 cavity is deep, the teeth stout and thick. The adductor scars are very long, 

 flabellate and extend almost to the anterior margin. They are bounded at 

 the sides by the thickened extension from the teeth but in front they are 

 not deeply impressed. TJiey are divided by a median septum which almost 

 reaches the margin. The diductor scar is elongate oval and posterior. 



The dorsal valve is more regularly convex though flattened medially 

 with angular slope in all directions. It is sinused on the anterior margin. 

 The beak is blunt and the margins slope away from it at a low angle. On 

 the interior the socket walls are stout and high, the sockets moderately 

 deep and the cardinal process rather feebly developed, being fused with the 

 adjoining walls and not projected beyond the hinge line ; it is not divided. 

 The muscular scars are posterior in a single or double subcircular pair 

 separated longitudinally by a broad low and short ridge. 



Dhncnsions. These shells measure in full growth about 15 mm in 

 width by i 2 mm in length. 



This peculiar little shell which is quite abundant bears the characters 

 of senility as expressed in its thickened shell and shell processes and the 

 usual resorption of the beak by the delth)Tium. It h-as the general charac- 

 ters of Rhipidomella modified to the expression presented by O r t h i s 

 dubia of the St Louis limestone \sce Pal. N. Y. v. 8, pt i, pi. 6A, fig. 

 18-22] which is a gerontic form with su.ch outline. 



Locality. At Lehuquet's beach, Grande Greve and eastward, near the 

 top of the series. 



Specific name. L huquet, a Jersey surname on the Forillon. 



Orthis (Rhipidomella) nov. ? 



Ventral valves of circular form, decidedly convex for the genus in the 

 umbonal region and with a uniform slope to the margins, bear rounded and 

 coarse radii, these slowly increasing by implantation except about the edge 

 where the radii are sharply defined on the internal surface. The muscular 

 area of the valve is distinctive in the shortness of the flabelliform scars 

 which are restricted to the posterior third of the valve. The hinge line is 

 quite short and distinctly elevated. Dorsal valve unknown. This appears 

 to represent a ver)- distinct species but we are not able to characterize it 

 further as specimens are not frequent in our material. 



Locality. Grande Greve, middle beds. 



