300 Lamarck’s Genera of Shells. 
Type. Ungulina transversa *. 
Shell transverse-rotundate, rugose, of a yellow-brown colour ; 
its width rather exceeds its length. 
2 Species. Locality unknown. PI. v. Fig. 35. 
6. Solenomya Tf. 
Shell inequilateral, equivalve, transversely elongated, obtuse 
at the extremities ; epidermis brown, shining, extending over the 
edges. Beaks not projecting, indistinct. One dilated, flattened, 
very oblique, cardinal tooth on each valve, slightly concave 
above, to receive the ligament. Ligament partly internal, partly 
external. 
The Solenomyz resemble the modiole, at first sight, but are 
allied, by their characters, to the solenes, and still more to the | 
anatine. They are thin shells, almost cylindrical, with di- 
verging rays from the beaks to the upper border and lateral 
extremities of the valves. 
Type. Solenomya Mediterranea t. 
Shell oblong, brown, smooth, radiated with yellow; valves 
near the nates undivided. 2 Species. New Holland. PI. v. 
Fig. 36. 
7. Amphidesma §. 
Shell transverse, inequilateral, suboval or rounded, some- 
times slightly gaping at the sides. Hinge with one or two 
teeth, and a narrow pit, to receive the interior ligament. _Liga- 
ment double ; one external, short, the other internal, and fixed 
in the cardinal pits. In some instances there are, besides the 
hinge teeth, more or less prominent lateral teeth. These shells 
are generally small. 
* Transverse. We have given the second species of Lamarck, instead of 
the U. oblonga, which is his type—not having been able to- procure that 
shell in time for the engraver. 
+ As being allied to the mye and solenenes. .We have taken the liberty, 
at the suggestion of a learned friend, to alter Lamarck’s name to the 
more expressive one, as above. 
$ Mediterranean. The second species of Lamarck, whose type is S. aus- 
tralis, a shell we have not been able to procure. 
§ From augu, circum, and Acjc¢, igamen, denoting its haying a ligament 
on both sides ; @. e. an internal, and an external. 
