356 A77ierican Seashelh 



Genus Botula Morch 1853 

 Subgenus Adula H. and A. Adams 1857 



Botula falcata Gould Falcate Date Mussel 



Plate 29k 



Coos Bay, Oregon, to Lower California. 



2 to 4 inches in length, very elongate, slightly curved. Beaks rounded 

 and about one-eighth the length from the anterior end; a strongly marked 

 angle occurs from the beaks to the base of the posterior extremity; numerous 

 vertical, wavy ribs over all the shell. Color a shiny chestnut-brown. Com- 

 mon. 



Botula californiensis Philippi Californian Date Mussel 



Plate 29h 



I to 1^4 inches in length, elongate, curved and smooth, except for a 

 velvety, hair-like covering over the posterior end. Shiny, chocolate-brown 

 in color. Moderately common. 



Genus Lioberus Dall 1898 

 Lioberus castaneus Say Say's Chestnut Mussel 



Both sides of Florida and the West Indies. 



% inch in length, oval-elongate, well-inflated and thin-shelled. Exterior 

 chestnut- to dark-brown, the anterior half glossy, the posterior half dull 

 and commonly with a fine grayish matting of periostracum. Interior bluish 

 white and with an irregular surface. Hinge simple with a slight swelling or 

 pad under the beaks. Moderately common in shallow water. 



Botula fusca Gmelin from North Carolina to southeast Florida (rare) 

 and the West Indies (common) is similar, but distinguished by its longer, 

 hooked or arcuate shape, by the thick, concentric ridges on the outside, by 

 the more anteriorly placed beaks, and by the tiny, vertical threads on the 

 hinge just posterior to the ligament. Attached in clusters to wood and 

 rocks. 



Genus Lithophaga Roding 1798 

 Lithophaga nigra Orbigny Black Date Mussel 



Plate 2 8in 



Southeast Florida and the West Indies. 



I to 2 inches in length, elongate and cylindrical. Black-brown outside 

 and an iridescent bluish white inside. Anterior lower third of each valve 



