FOSSILS OF THE DEVONIAN. ib 
of a ventral valve, where this area and the space occupied by the anterior 
adductor scars in the dorsal valve is occupied by the short, strong ramuscules 
from the great sinuses. Over the central portion of the cast the radiating 
lines of the inner surface of the shell are seen crossing the muscular scars 
and vascular markings, and somewhat complicate the study of the latter. 
The draughtsman has represented these, as also all the details, with accuracy. 
On comparing this with the interior of the corresponding valve of 
Lingula Elder, of the Trenton limestone of Wisconsin, described by Prof. 
R. P. Whitfield,* we observe in the latter the strong extension of the great 
pallial sinuses nearly around the posterior end of the perivisceral cavity 
and back of the divaricator scar; the greater anterior expansion of the pal- 
lial sinuses, and the smaller area of the adjustor muscular scars. The 
former character is unknown in L. Whitei, but is present in the recent spe- 
cies so beautifully illustrated by Hancock.® 
The two paleozoic species possess, however, the large posterior ad- 
ductor scars, the postero-lateral adjustor scars, and the absence of the inner 
ramuscules of the posterior extension of the pallial sinuses, features that 
distinguish them from Lingula anatina and other living species. 
The character of the anterior ramifications of the great sinuses of _L. 
Whitei resembles that of ZL. affinis more closely than that of any other 
species. 
To afford the means of a direct comparison between the Silurian, De- 
vonian, and a recent Lingula, an outline figure of the interior of the dorsal 
valve of a species from each horizon is given on plate xxi, figs. 18, 19, and 
20, in which the muscular scars and vascular markings of each are shown. 
The specific name of the Devonian species is given in honor of Dr. Q. 
A. White, geologist and paleontologist. 
Formation and locality—Lower portion of the Devonian limestone, 
southwest spur of Atrypa Peak, Eureka District, Nevada. 
® Amer. Jour. Sci., 3d ser., vol. xix, p. 472, 1880. 
* Organization of the Brachipoda, by Albany Hancock, esq., 1858. Trans. Royal Phil. Soo., pls. 64-66. 
