Report of the state Geologist. 549 



anterior ends toward the more conspicuous, and apparently com- 

 pound central scar. 

 Type, LinguleUa Damsi, ftfcCoy (sp.). 



I.higultlla Kiln, Hail and Whitfield. Fig. 240.— Dorsal aspect, showing: pedicle-area. 

 Fig. 241 —Internal cast of pedicle-valve. Fig. 242.— Internal cast of brachial valve. 

 (Walcott.) 



Distribution. Cambrian — (?) Lower Silurian. 

 It is possible that the Devonian (Hamilton) species Lingula 

 paMforwiis, Hall, belongs to this genus. 



Lingulops, Hall. 1871. 

 (Plate 1, Figs. 18-20.) 



Shells small, linguloid; both valves with a relatively broad 

 cardinal area, which is divided transversely into two parts, (a) 

 a smooth, narrow, apical portion ; (b) a broad inner band, along 

 which the valves appear to have been in contact. This band is 

 flattened and projects into the interior cavity of the shell, like a 

 narrow lunate shelf ; on the pedicle-valve it is concentrically 

 striated or smooth, and gently convex. The pedicle-groove 

 crosses this inner area only, not encroaching on the apical area 

 of either valve. Directly in front of the cardinal area, is a nar- 

 row crescentic ridge, the anterior margin of which is deeply 

 excavated. This ridge, which is parallel and co-extensive with 

 the cardinal area, bears a median angulation, projecting back- 

 ward toward the pedicle-groove. 



In the interior of the pedicle-valve is an elongate median mus- 

 cul »r scar accompanied by two pairs of lateral scars. The median 

 portion of the muscular area is thickened, forming an incipient 

 platform, from the anterior edge of which extends a median 

 septum. The posterior margin of the muscular area bears a 

 trilobed parietal scar. 



The interior of the brachial valve shows the cardinal area, 

 pedicle-groove and the crescentic ridges essentially as on the 



101 



