248 PALEONTOLOGY OF NEW YORK. 



by a narrow median cardinal process. The inner moiety of the crural plates 

 is deflected to a vertical or slightly divergent position, and in this form they 

 are produced anteriorly. These plates rest upon two broadly convergent septa 

 which unite with the valve making a sessile spondylium, wliich is acute at its 

 anterior extremity, and lies at, or in front of the center of the valve. The 

 character of this structure in the brachial valve is not variable in Gypidula. 



The typical species of this genus is the Pentamerus occidentalis ( = P. comis, 

 Owen), from the middle Devonian of Iowa, a shell whicli is usually more or 

 less plicate, though these plications constantly show a tendency to obsolescence. 

 With it are to be associated the G. IcEvhiscula, Hall, a small, smooth species, G. 

 mundula, Calvin, also from the Iowa Devonian, G. subglobosa, Meek and Wor- 

 then, from the Hamilton fauna at Rock Island, Illinois; G. Romingeri, sp. nov., a 

 large, strongly plicate shell from the Hamilton fauna at Alpena, Michigan, and 

 G. Lotis, Walcott, from the " Upper Devonian, on the Avest side of Applegate 

 Canon, White Pine Mining District, Nevada."* The type was not one of long 

 duration, and appears to be altogether absent from the New York faunas. 



Genus CAPELLINIA.f gen. nov. 



PLATE I.XX. 



Shells large, elongate subovate ; the relative size and convexity of the valves, 

 normal for Pentamerus, are here reversed, the brachial valve being the larger 

 and deeper, with full, strongly arcuate and incurved umbo and beak, the apex 

 of which is concealed within the delthyrium of the opposite valve. The 

 pedicle-valve has an acute suberect beak which is not arched posteriorly, but 

 rises directly from the cardinal margins. Below it is a broad delthyrium with- 

 out evidence of deltidial plates ; there is no hinge-line, but the margins of the 

 delthyrium make subacute angles with the lateral margins of the valve. Car- 

 dinal slopes very broad and abrupt. The surface of the pedicle-valve is flat- 

 tened above, while that of the brachial valve is evenly and deeply convex ; it 

 also shows a tendency to trilobation or obscure radial plication. The arrange- 



* Palfeontology of the Eureka District, p. 161, pi. iii, fig-. 9. 



t Dedicated to Cav. Giovanni Capellini, Pi-ofessor in Bologna and Senator of tiie Kingdom of Italy ; iu 

 recog-idtion of his scientific achievements, and in gi-atefu! recollection of a personal friendship of many years. 



