BRACHIOPODA. 11 



scars. Thesamemay be said of the other scars, all of which show something of this 

 progressive increase in size. The impressions which appear to be most gener- 

 ally retained among the fossils are the anterior laterals (j) of the brachial valve, 

 and the middle laterals (k) of the pedicle-valve. These lie in the ante-median 

 portion of the valves, and, in their progress forward, have left long, conspicu- 

 ous tracks which follow the axis of the shell. 



The separate members of these pairs of impressions are not always, or even 

 often, to be distinguished, the long axial impression accompanied by the ante- 

 rior portions of the broad centrals being usually all that is visible of the mus- 

 cular scars. The subdivision and asymmetry of these scars in L. anatina has 

 been determined only by the aid of the attached muscular bands. Without their 

 assistance it would prove difficult, if not impracticable, to ascertain their exact 

 limitations, merely from the impressions upon the shells. This will, to a certain 

 degree, be made evident by comparing Professor King's figures with those of 

 the same species given on Plate I ; in the latter drawings the scars have been 

 somewhat emphasized, but it is impossible to resolve, with any degree of 

 accuracy, the compound lateral and transmedian scars {k, I, i, in the brachial, j, i, 

 in the pedicle-valve). Nevertheless, in the brachial valve of L. Wliitii, the com- 

 pound lateral scar is quite distinct, and the umbonal (g) impressiou well defined. 

 On the brachial valve of L. Elderi, Mr. Whitfield has shown the former to be 

 even more clearly defined than in L. Whitii, and the umbonal scar to be un- 

 usually large. In both these species, the laterals and transmedians are situated 

 considerably nearer the umbonal region than in L. anatina. The pedicle-valve 

 of I/. Eldei-i shows the transmedian scars, which are represented as two on each 

 side, the anterior of wdiich is regarded by the author as the scar of the 

 "posterior adjustors" (transmedian) and "anterior adductors" combined. 

 Lingula punctata shows comparatively broad muscular scars in this region, but 

 it has been impossible to resolve them satisfactorily. The umbonal scar also, 

 appears on the pedicle-valve of L. Elderi. 



A species of Lingula from the Cuyahoga shale at Johnstown, Chardon, and 

 elsewhere in Ohio, which has usually been confounded with the common L. Melie 



