109 



Perna ephippium 



obliqua 



isognomon 



avicularis 



femoralis 



Perna canina 



marsupiom 



sulcata 



vulsella 



nucleus. 



[And two fossil species.] 



MALLEUS. 



OSTREA. MALLEUS. LinUCEUS. 



Sowerby's Genera, No. 6, plate 2. 



The genus Malleus of Lamarck, like the preceding, 

 was by Linnaeus included in the G. Ostrea, it in some 

 respects approximates the Perna, but the hinge is very 

 different, and more nearly resembles thatof the Avicula, 

 though it cannot be mistaken for it, both being without 

 the sulcated teeth or joints at the hinge; but the coni- 

 cal cavity, situated under the apices of the Malleus, and 

 crossing the angle of the ligamental slope, decidedly dis- 

 tinguishes it from the Avicula; the valves also, though 

 irregular, are of the same size, without any notch or si nus 

 on either side, which is not the case in the G. Avicula. 

 The singular long pickaxe shape of the base of these 

 shells is very remarkable; they possess no elegance 



