42 The Paleontologist. [June lo, 



shell farther forward, and more or less deflected at the extremities of dif- 

 ferent specimens ; lateral margins sloping inward at first, then rounding 

 regularly to the front. Cardinal line of the dorsal valve linear, straight 

 and slightly projecting over the area of the other valve ; umbone flat, 

 slightly concave near the beak in most cases, more or less highly convex 

 at the middle, of different examples, and curving abruptly to the lateral 

 and front margins. Surface covered with crowded, radiating striae, which 

 are fine and delicate at and just below the beak, becoming larger as they 

 advance toward the margins where they are rounded and strong; striae 

 increased, as the surface widens, by implantation, but not always of a 

 uniform size; in some cases they vary considerably, and are irregularly 

 arranged, from one to three or four of the smaller placed between two of 

 the larger. Unworn examples show the whole surface covered with very 

 fine, delicate, sharp, crowded, concentric, raised lines, crossing the ra- 

 diating striae, which are distinctly seen under an ordinary magni- 

 fier. About ten of the radiating stride in the space of one line, at a quarter 

 of an inch forward of the beak, and three or four near the free margins. 



Ventral vd\wQ\ a strongly marked deltidium ; cardinal area flat and 

 moderately broad, sloping gently each way from the projecting beak, 

 to the extremities of the lateral margins, and standing at an angle of 

 70 degrees or more with the dorsal valve ; convex near the beak, and 

 on the umbone ; and different examples more or less deeply concave 

 near the middle, curving, to correspond with the other valve, to the 

 free margins. Surface of this valve covered with radiating striae and 

 concentric lines, similar to the dorsal valve. 



The only feature of the interior of this species that can be referred to 

 at this time, is the deltoid process of the dorsal valve, which differs materi- 

 ally from specimens and figures of other species ; it is prominent, stands 

 at a high angle with the valve, is bi-lobed, each lobe divided by a deej3, 

 strong depression or slit, commencing at the beak and widening to the 

 ends of the lobes. 



The breadth of the shell along the cardinal line, of different specimens, 

 varies from ij to 2 J inches, and from i to over \\ inches from beak to 

 front. Other examples, supposed to i)e the young of this species, are 

 much smaller. In outline and dimensions most of the specimens re- 

 semble some forms of Strophomena alternata, Conrad. 



Some of these specimens, with other species, were loaned to the late 

 Mr. Meek, and used in making up his descriptions for the first volume 

 of Ohio Paleontology. In referring to this species, he said : 



' ' I am left in some doubt, however, whether the form called 5". neglecta, 

 in Mr. James' list, is the same species as the filitexta, not having seen 

 specimens showing its internal characters. Most of Mr. James' type 

 specimens of that shell show little or no difference of form from those 

 here referred to S. filitexta. One of them, however, is much more 

 elongated on the hinge line, and evidently had more acutely angular 

 lateral extremities. They all, likewise, have nearly the same-sized 

 striae, but the striae are much more distinctly crenated by the crossing of 



