119 



in clusters. The valves are both of them strongly 

 plaited within and without, closely interlocking with 

 each other. Shell inequivalve, not eared, narrowed 

 towards the base, superior margin round, plaited, or 

 strongly ribbed, summits unequal, and without external 

 facets. Hinge with two strong teeth in each valve; a 

 cavity between the primary teeth, in which the liga- 

 ment is internally inserted. 



Plicatula ramosa Plicatula cristata 



depressa reniformis 



Plicatula austral is. 

 [There are also six fossil species.] 



SPONDYLUS. 



spondyi.us GjEDAropus. — Linn. 

 MawesLinnceus, pl.2,f. 1, 4. 



Soiverbys Genera, No. 9, plate 1, 2 

 This numerous and beautiful family, out of which La- 

 marck has only constituted one new genus, the G. Plica- 

 tula, (Spondylus plicatusof Linnaeus,) has long requir- 

 ed a distinctive arrangement of the species, all of which, 

 with the exception of the Spondylus regius, were called 

 by Linnaeus, S. Gaedaropus. Lamarck describes twen- 



