434 Anicriatn Seashells 



Aiacoma incongnm von Martens (fig. 88b) (Alaska to Washington) is 

 similar, but more oval, with a more pointed slope at the beaks, a straighter 

 posterior dorsal edge. Its upper pallial sinus line, after nearly reaching the 

 anterior muscle scar, turns downward and then runs anteriorly before con- 

 necting with the paUial sinus. Common in Alaska. 



Genus Apoly metis Salisbury 1929 

 Apolymetis intastriata Say Atlantic Grooved Macoma 



Plate 32y 



South half of Florida and the Caribbean. 



2 to 3 inches in length, elliptical, fairly thin but strong and all white in 

 color. The shell is strongly twisted. At the posterior end, the right valve 

 bears a strong, radial rib, while on the left valve there is a fairly strong, radial 

 groove. Pallial sinus very large. Living specimens are not commonly col- 

 lected, although shells are commonly washed ashore. 



Apolymetis biajigiilata Carpenter Pacific Grooved Macoma 



Santa Barbara, California, to Ensenada, Mexico. 



2 to 3 V2 inches in length, oval, moderately compressed, strong, and dull 

 grayish white in color. Interior glossy-white with the central portion blushed 

 with pastel-peach. Left valve with a shallow, radial groove near the posterior 

 end. Right valve with a corresponding ridge at the end of which the margin 

 of the shell is shallowly notched. Alias A. alta Conrad. Common. 



Family SEMELIDAE 

 Genus Semele Schumacher 18 17 



Resilium supported in a horizontal, chondrophore-like depression which 

 is internal and parallel with the hinge line. 2 cardinal teeth in each valve. 

 Right valve with 2 distinct lateral teeth, but practically absent in the left 

 valve. The ligament is external. 



Semele proficua Pulteney White Atlantic Semele 



Plate 40g 

 North Carolina to south half of Florida and the West Indies. 



/4 to 1/4 inches in length, almost round, beaks almost central. Lunule 

 small and pushed in. Fine concentric lines and microscopic radial striations. 

 Externally whitish to yellowish white. Interior glossy, commonly yellowish, 

 rarely speckled a little with purple or pink. Moderately common in shallow 

 water. The color form radiata Say, has a few indistinct radial rays of pink 

 (pl.400. 



