MANUAL OF THE MOLLUSCA. 
Shell resembles that of Tropidoleptus, but the dental processes 
are not crenulated, nor distinctly separated from the area as ia 
that genus. 
AMPHICIINA, Laube, 1865. 
Etymology, amphi, about, and clino, a slope. 
Type, A. dubia, Minster (Producta). 
Shell inequivalve circular, excavated, smooth; ventral valve 
convex, beak short ; perforated ; dorsal concave ; hinge line very 
short and suboblique; area wanting; deltidium triangular, dis- 
tinct; structure of the test fibrous, squamose; externally 
Amphiclina resembles some Leptzenze, the shell structure is very 
similar. 
Distribution, 2 speciés. St. Cassian, Austria. 
Calceola. ‘‘ Within the last few years the researches of Pro- 
fessors Suess and Lindstrém have thrown considerable doubt as 
to this genus belonging to the Brachiopoda.” . . ‘‘Ifa bra- 
chiopod it séems the most abnormal of all its genera.”—Dayid- 
son (1865). 
Famity VIII.—Lincuripvz.* 
LINGULELLA, Salter, 1866. 
Etymology, diminutive of Lingula. 
Type, Lingula Davisu, M‘Coy. 
‘Shell nearly equivalve, broad oblong, the ventral valve 
pointed, with a distinct pedicle-groove. Muscular sears 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.”’—(Salter. ) . 
Distribution, 8 species. Lower Silurian. Ireland, Wales, 
Norway. 
LINGULEPIS, Hall, 1868. 
Etymology, lingula, a little tongue ; lepis, a scale. 
Type, Lingula pinniformis, Owen. 
Shell thin, suboyate, or subtrigonal; composition and struc- 
ture asin Lingula. Ventral or larger valve with beak more or 
less produced and pointed; visceral scar trilobed, with a longi- 
tudinal 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, 
Distribution, 4 species. Silurian, America. 
* See p. 390. 
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