MARGAIUTIFERA. 



525 



The hinge-margin in these shells is usually prolonged 

 into unequal, wing-like ears, and the epidermis is often 

 produced at the margin of the valves into a fringe. The 

 pearly nacre does not extend to the ventral edge of the 

 valves, and the byssus is often cylindrical and solidified. 

 The species are inhabitants of the British Islands, the 

 Mediterranean and Ked seas, the Indian and Pacific oceans, 

 and the coasts of South America. 



Species of Avicula. 



brevicauda, Desk. 

 costellata, Lam. 

 crocea, Chem. 

 Georgiua, Quay. 

 heteroptera, Lam. 

 birundo, Linn. 

 Largillierfi, Phil. 

 lingulata, Desh. 

 livida, Desh. 

 macroptera, Lam. 

 marrnorata, Phil. 

 meleagridis, Chem. 



morio, Leach. 

 physoides, Lam. 

 pica, Phil. 

 rufa, Dkr. 

 Savignyi, Desh. 

 sernisagitta, Lam. 

 serrulata, Dkr. 

 sterna, Gould. 

 tortirostris, Dkr. 

 vespertilio, Desh. 

 virens, Lam. 



Genus margaritifera, Browne. 



Shell orbicular or sub-quadrate, sub-equivalve ; surface 

 of valves squamose, pearly within, not eared or winged 

 posteriorly ; right valve with a byssal sinus. Hinge linear, 

 edentulous; ligament marginal, elongated, nearly external, 

 dilated in the middle. Posterior muscular scar large and 

 sub-central. 



Syn. Margaritophora, Muhlf. Unionium, Link. Pinc- 

 vol. ir. 3 v 



