38 CONCHOLOGY. 



U. transversa. The transverse Ungulina. 



Shell vertical or longitudinal, rather irregular, not gaping, 

 equivalve, inequilateral, with summits little marked and de- 

 corticated ; hinge dorsal, formed by one short, primary cleft 

 tooth, before an oblong pit, divided by a small ligament, in 

 which is inserted a sub-interior ligament; colour yellowish 

 brown. 



6. Solenimya. Two species. 

 This genus, which at first sight is confounded with the 

 Solens, differs from them particularly by the singular dis- 

 position of the ligament placed at the short side of the shell. 

 Solenimya Australis. Solenimya Mediterranea. 



S. Australis. The Australian Solenimya. PI. 6, fig. 2. 



Shell covered with a thick brownish epidermis, regular, 

 thick, elongated oval, edges straight and parallel, equally 

 rounded at both extremities ; valves equal, very inequilateral. 



S. Mediterranea. The Mediterranean Solenimya. 

 Transversely oblong ; dark brown, ribbed longitudinally, 

 with imbricated projecting foliations ; inside white. 



7. Amphidesma. Sixteen species. 



This genus was constituted by Lamarck on account of 

 the peculiar characters which distinguished it from those 

 genera which it most resembles ; particularly in having the 

 valves connected by two ligaments. 



Shell generally small, transverse, suboval or rounded, 

 occasionally a little gaping at the sides ; hinge with one or 

 two cardinal teeth, and a narrow cavity for the interior liga- 

 ment ; exterior ligament short. 



Amphidesma variegata. Amphidesma flexuosa. 



A. donacilla. A. prismatica. 



A. lactea. A. phaseolina. 



A. cornea. A. corbuloides. 



A. albella. A. glabrella. 



