SCACCIIIA. 471 



on each side, united behind. Foot vermiform, ending in an 

 erectile gland, channelled throughout its length. 



Shell sub-orbicular. Hinge with two diverging, bifid 

 primary teeth ; lateral teeth none ; cartilage marginal, 

 linear. Siphonal inflection none, or rudimentary. 



Genus UNGULINA, Daudin. 



Mantle-margins fringed ; palpi pointed. 



Shell sub -orbicular ; surface of valves covered with a thick, 

 wrinkled, sometimes dark-coloured epidermis. Hinge-teeth 

 two in each valve ; ligament very short. Muscular impres- 

 sions long, rugose. 



Ex. U. rubra, Roissy, pi. 114, fig. 4, 4, a. 



The species of Ungulina are found buried in sand and 

 mud on the shores of the Mediterranean and the Eed Sea. 

 The foot is long, cylindrical, and tubular, with a sort 

 of erectile gland at the extremity ; and the palps are long 

 and pointed. 



Species of Ungulina. 



alba, Rang. transversa, Lam. 



rubra, Roissy. 



Genus SCACCHTA, Philippi. 



Mantle widely open. Foot compressed, linguiform. 



Shell ovate, transverse, thin, smooth, equivalve, inequi- 

 lateral, slightly truncate posteriorly. Hinge with one or 

 two small cardinal teeth in each valve ; lateral teeth plici- 

 form, or obsolete ; ligament small, external ; cartilage inter- 

 nal, inserted in an oblong pit. Muscular impressions small, 

 rounded, sub-equal ; pallial line simple, without a sinus. 



Ex. S. elliptica, Scacchi, pi. 114, fig. 5, 5, a. 



