390 MANUAL OF THE MOLZUSCA. 
SIPHONOTRETA, Verneuil. 
Hiymology, siphon, a tube, tretos, perforated. 
Types, 8. unguiculata, Hichw., Figs. 199, 201. 8. verrucosa, 
Fig. 200. 
Shell oval, bi-convex, slightly beaked, conspicuously punctate, 
or spiny; beak perforated by a tubular foramen ; hinge-margins 
Fig. 199. Fig. 200. Exterior. Fig. 201. Interior, 
thickened ; ventral valve with four close adductor scars sur- 
rounding the foramen. ‘The spines are tubular, and open into 
the interior of the shell by prominent orifices. (Carpenter.) 
S. anglica, Morris, has moniliform spines. 
Fossil, 9 species. Lower and Upper Silurian. Britain, 
Bohemia, Russia. 
? Acrotreta (sub-conica), Kutorga. 3 species. Lower Silurian, 
Russia. Shaped lke Cyrtia, with an apical foramen; no 
hinge. 
Famity VIII.—LINnGcuLivz. 
Shell oblong or orbicular, sub-equivalve, attached by a pedicle 
passing out between the valves; texture horny, minutely 
tubular. y 
Animal with a highly vascular mantle, fringed with horny 
setee; oralarms thick, fleshy, spiral, the spires directed inwards, 
towards each other. 
Lincua, Bruguiére. 
Etymology, lingula, a little tongue. 
Type, L. anatina, Pl. XV., Fig. 32. 
Shell oblong, compressed, slightly gaping at each end, trun- 
cated in front, rather pointed at the umbones; dorsal valve 
rather shorter, with a thickened hinge-margin, and a raised 
central ridgo inside. 
