146 ANATINID^. 



both ends, surface scabrous ; hinge with a long, horizontal exca- 

 vated cartilage-process ; ligament placed in a deep groove. Pel. 

 brevifrons, H. 4ds. (cviii, 62, 63), is the type of the group, which 

 differs from Periploma by the want of an internal rib below the 

 cartilage-process and by not having the beaks fissured. 



Alicia, Angas, 186T. 



Distr. — 2 sp. Port Jackson. Australia. A. angustata, Angas 

 (cviii, 64, 65). 



Shell inequivalve, resembling a small Thracia, but the pos- 

 terior portion is much smaller than the anterior, internally sub- 

 nacreous ; beaks entire ; hinge composed of a posterior callus 

 in the right valve fitting in a cavity in the left one, and an 

 anterior marginal tooth or ridge ; cartilage internal under the 

 umbones, covered by a large triangular ossicle ; pallial line 

 deeply sinuated. 



Lyonsia, Turton, 1822. 



Syn. — Magdala, Leach, 1821. Hyatella, Brown. Pandorina, 

 Scacchi. 



Distr. — 18 sp. Greenland, ISTorth Sea, Norway, West Indies, 

 Madeira, India, Borneo, Philippines, Peru. Fossil ? Miocene — ; 

 Europe. (100 sp. Lower Silurian — . D'Orbigny.) 



Shell nearly equivalve, left valve largest, thin, subnacreous, 

 close, truncated posteriorly ; cartilage-plates oblique, covered 

 by an oblong ossicle ; pallial sinus obscure, angular. Structure 

 intermediate between Pandora and Anatina ; outer layer com- 

 posed of definite polygonal cells. 



Animal with the mantle closed ; foot tongue-shaped, grooved, 

 byssiferous ; siphons very short, united nearly throughout, 

 fringed ; lips large, palpi narrow, triangular. 



L. Norvegica (cviii, 66) ranges from Norwa}^ to the sea of 

 Ochotsk ; in 15-80 fathoms. 



LYONSiELLA, Sars, 1868. L. abyssicola^ Sars. 



SOULEYETIA, Becluz. Shell inequilateral, spoon-like process 

 directed backwards. 



? ENTODESMA, Phil. Shell thin, Saxicava-shaped, slightly inequi- 

 valve and gaping, covered with thick epidermis ; hinge edentu- 

 lous ; each valve with a semicircular process containing the 

 cartilage. Ossicle and pallial impression not observed. E. 

 Chilensis, Phil, (cviii, 6*1). 



(Anatiri!^.) 



Mostly fossil. The classification is very unsatisfactorily 

 known. Some forms are tumid and cordate, like the recent 

 Mytilimerise or the fossil Cercomyae, and others are elongated 

 and considerably compressed, as the typical Anatinse and the 



