186 CORBULIDiE. 



from wliich we derive our own description and delineation 

 are declared to have been (once) dredged at Weymouth, in 

 Dorsetshire. They are not, however, quite mature, so 

 that it is necessary to amend their characters from adult 

 examples, which appear in tolerable abundance, but with- 

 out any locality appended, in some of the larger general 

 collections of shells. 



The shape is oval, and a little triangular, and the valves 

 for their genus are not much inequilateral or swollen, 

 although both are tolerably ventricose, and their sides 

 clearly unequal. It is, perhaps, less solid than the average 

 of Corhidce, but is tolerably strong, opaque, and when adult 

 of a roseate buff or dark fulvous, Avith two short rays, of 

 a brownish rose-colour, which so widely diverge ft-om the 

 beaks on either side as almost to run parallel with the dor- 

 sal margins : these rays are of a purplish rose-colour in the 

 young, where the ground is whitish, and the smaller valve 

 at least covered with a glossy yellowish brown epidermis. 

 The inequality of the valves, although manifest, is not 

 greatly displayed at the umbones, that of the larger one 

 not projecting beyond the other in so marked a manner as 

 in nucleus. This distinction, however, although observable 

 in the young, is most evident in the adult, which is ex- 

 tremely glossy, a character not belonging to the preceding 

 species, and preserved, although faintly, in the younger 

 examples. The smaller valve is almost smooth, the larger 

 Is grooved in the young, with fine and closely-disposed 

 simple sulci, which almost entirely disappear in the adult, 

 usually leaving its entire area devoid of sculpture, except- 

 ing at the broader end, and closely adjacent to the ventral 

 margin. This latter is moderately arcuated, but always 

 less so than in nucleus. The beaks, which are but slightly 

 inclined and a little acute, being situated only a little In 

 advance of the middle, the sides do not greatly differ in 

 length ; both extremities are attenuated, and the front one 

 is rounded, but not symmetrically, whilst the hinder Is 

 narrowed to a very bluntly subbiangulated point. The 

 dorsal edges are almost equally and very moderately 



