172 Systematic Palkoxtolocy — ^Iiddle Devoxiax 



Camarotoechia conprcr/ata Schuchert, 1897, Bull. U. S. Geol. Surv., No. 87, 



p. 165. 

 Camarotoechia congregata Clarke, 1903, N. Y. State Mus., Bull. 65, p. 203. 



Description. — Hliell rolnist, varying from sliort-ovate to subglobose; 

 length and width nearly equal or a little wider than long; front rounded 

 or straight in the middle; sides curved abruptly; apex pointed. Ventral 

 valve with a moderate sinns -which often begins at about one-third the 

 length from the apex and becomes conspicuous towards the front; beak, 

 in old shells, clo.sely arcuate over the apex of the opposite valve, in young 

 shells, nearly straight or slightly incurved. Dorsal valve gibbons in old 

 shells, regularly convex in young specimens; mesial fold scarcely con- 

 spicuous on the upper half of the shell, sometimes prominent near the 

 margin ; in the interior a distinct septum reaching half the length of the 

 valve. Surface, in young shells, marked by nine or ten distinct sub- 

 angular or rounded plications; in older shells, by eighteen to twenty-two, 

 of which three or four occupy the mesial sinus and foiir or five the mesial 

 fold; there are also slender concentric striae, which are sometimes a little 

 imbricated near the front margin. 



This species occurs in some of the coarse arenaceous shales of ]\Iary- 

 land ; but it is not common except in occasional thin zones, specimens 

 from which agree fairly well with those of the JSTew York Hamilton. The 

 broader forms of the Maryland specimens agree in form, and in number 

 and strength of plication,*, fairlv Avell with the Xew York type specimens. 

 There are others which are more pointed than most of the ISTew York 

 specimens, while the plications are more slender. The species is char- 

 acterized by its robust form, abrupt curvature of sides, rather moderate 

 fold and sinus with the exception that the latter is well marked toward the 

 front of the shell, three or four ])lications in the sinus and four or five 

 on the mesial fold. 



Length, 12-19 mm.; width, 12-19 mm. 



Occurrence. — Eomney Formation, Hamiltox ^Iember. B. & 0. E. K. 

 cut at 21st Bridge ( ?) . Western Md. ; Williams Road, 3I/2 miles southeast 

 of Cumberland ; on the Hancock-Harrisonviile Eoad about 2 miles north 

 of Hancock ; in run at Hancock, east of Catholic church ; along Flintstone 

 Creek in fiilpin (?) ; west of iron bridge over Town Creek northeast of 



