342 LINGULIDA. 
Lingule existed in the British seas as late as the period of the 
Coralline Crag. The recent species have been found at small 
depths, and even at low-water half buried in sand. JZ. Davisii, 
Lower Silurian, Tremadoc, has a pedicel-groove like Obolus. 
GLoTTIDIA, Dall, 1870. Shell with two diverging internal 
lamin in the neural valve proceeding from the beak, and a 
mesial septum in the hemal valve; otherwise like Lingula. 6 
recent sp. EK. and W. coasts of North America. J. albida, 
Dall. California. 
LINGULELLA, Salter, 1866. (Htym.—Diminutive of Lingula.) 
“* Shell nearly equiv alve, broad, oblong, the ventral valve pointed, 
with a distinct pedicel-groove. Muscular scars strong, nearly 
as in Obolus, but the pair of anterior retractors are more linear 
than in Obolus, and the sliding muscles small, and not quite 
external as in Obolus.”—SattTer. 3 sp. Cambrian, Lower Sil- 
urian; Ireland, Wales, Norway. JL. Vavisii, M’Coy. 
LINGULEPIS, Hall, 1863. (Htym.—Lingula, a little tongue; 
lepis,ascale., Shell thin, subovate, or subtrigonal; composition 
and structure as in Lingula. V entral or larger valve with beak 
more or less produced and pointed ; visceral scar trilobed, with 
a longitudinal raised mesial line or septum—lateral divisions 
diverging , and usually longer than the middle one; dorsal or 
smaller valve with the beak less produced than that of the other ; 
visceral scar flabelliform. 4sp. Cambrian; America. J. pin- 
niformis, Owen. 
DIGNOMIA, Hall, 1873. With strong internal median septum, 
otherwise asin Lingula. Silurian—Devonian; U.S. JZ. alveata, 
Hall. 
