390 



MANUAL OF THE MOLLUSCA, 



SiPHONOTRETA, Yemeuil. 



Eti/mologi/, si/phon, a tube, trefos, perforated. 



Tyi^es, S. unguiculata, Eichw., Pigs. 199, 201. S. verrucosa, 

 Fig. 200. 



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

 or sj)iny ; beak perforated by a tubular foramen ; hinge -marging 



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 j)rominent orifices. (Carpenter.) 

 S. anglica, Morris, has moniliform spines. 



Fossil, 9 species. Lower and Upper Silurian. Britain, 

 Bohemia, Eussia. 



? Acrotreta (sub-conica), Kutorga. 3 species. Lower Silurian, 

 Russia. Shaped like Cyrtia, with an apical foramen ; no 



hinge. 



Family YIII. — Lingulidje. 



Shell oblong or orbicular, sub-equivalve, attached by ajDedicle 

 passing out between the valves ; texture horny, minutely 

 tubular. 



Animal twith a highly vascular mantle, fringed with horny 

 setae ; oral arms thick, fleshj^, spiral, the spires directed inwards, 

 towards each other. 



Lingtjla, Bruguiere. 



Etymology, lingidci, a little tongue. 



Type, L. anatina, PI. XY., Fig. 32. 



Shell oblong, compressed, slightly gajDing at each end, trun- 

 cated in front, rather pointed at the umbones ; dorsal valvo 

 rather shorter- with a thickened hinge -margin, and a raised 

 central ridgo inside. 



