CONCHOLOGIA CESTRICA. 7. 
Sub-genus MENETUS, H. and A. Apams, 1853. 
Shell, depressed; whorls rapidly increasing; periphery 
angulated. 
M. exacutus, SAY. 
Planorbi§ exacutus, Say, Jour. Acad. Phila. F. S., II., 
1O2Z1. 
M. exacutus. — [W. G. B.] M. exacutus (abnormal). 
Fig. 141, Fig, 142, 
5 & 
Shell, small, depressed; whorls 4, wider than long, 
carinated on the circumference; umbilicus broad, and 
deep; aperture below the carina, and angulated by it. 
H. 1%, W. 4, mill. 
Station, ponds. Pickering Creek, Chester County. 
Sub-genus GYRAULUS, Agassiz, 1837. 
Shell, orbicular above, flat beneath; whorls few, 
rapidly increasing. 
G. deflectus, Say. 
Planorbis deflectus, Say, Long’s Exped., enh 
i 1824, Fig. 143. 
Shell, small, depressed; whorls nearly 5, CX 
flattened, smooth, fine striate; margin ob- 
tusely carinate; last whorl deflected down- 
wards near the aperture; which is large and 6) 
very oblique. H. 2, W. 6, mill. 
Station, ponds and rivulets. Pickering Creek, Ches- 
ter County ; frequent. 
