390 



MANUAL OF THE MOLLUSC A, 



SiPHONOTRETA, Verneuil. 



Fjtymology , siphon, a tube, tretos, perforated. 



Types, S. unguiculata, Eichw., Figs. 199, 201. S. verrucosa, 

 Fig. 200. 



Shell oval, bi-convex, slightly beaked, conspicuously punctate, 

 or sj^iny ; beak perforated by a tubular foraraen ; hinge-margina 



Fig. 199. 



Fig. 200. Exterior. 



Fig. 201, Literior. 



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 like Cyrtia, with an apical foramen ; no 

 hinge. 



Family VIIL — Lingulid^. 



Shell oblong or orbicular, sub-equivalve, attached by a pedicle 

 passing out between the valves; texture horny, minutely 

 tubular. 



Animal -with a highly vascular mantle, fringed with horny 

 setae ; oral arms thick, fleshy, spiral, the spires directed inwards, 

 towards each other. 



Lingula, Bruguiere. 



Etymology, lingula, a little tongue. 



Type, L. anatina, PI. 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 

 co]itral ridge inside. 



