146 ANATINIDZ. 
both ends, surface scabrous; hinge with a long, hor!zontal exca- 
vated cartilage- -process ; ligament placed in a deep groove. Pel. 
brevifrons, H. Ads. (eviii, 62,63), is the type of the eroup, whieh 
differs from Periploma by the want of an internal rib below the 
cartilage-process and by not having the beaks fissured. 
Auxtcra, Angas, 1867. 
Distr.—2 sp. Port Jackson, Australia. A. angustata, Angas 
(evili, 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; pullial line 
deeply sinuated. 
Lyonsra, Turton, 1822. 
Syn.—Magedala, Leach, 1827. Hy eae Brown. Pandorina, 
Scacchi. 
Distr.—18 sp. Greenland, North 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 Norway to the sea of 
Ochotsk ; in 15-80 fathoms. 
LYONSIELLA, Sars, 1868. JL. abyssicola, Sars. 
SOULEYETIA, Recluz. 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. Z£. 
Chilensis, Phil. (evili, 67). 
(Anatine.) 
Mostly fossil. The classification is very unsatisfactorily 
known. Some forms are tumid and cordate, like the recent 
Mytilimerize or the fossil Cercomyze, and others are elongated 
and considerably compressed, as the typical Anatinze and the 
