SPONDYLIDAE 369 



are attached to rocks and become quite massive like Spojidyhis. For con- 

 venience, we are considering it a full genus. 



Himjttes multirugosiis Gale Giant Rock Scallop 



Plate 29a 



Aleutian Island to Lower California. 



Up to 8 inches in length. A heavy massive shell characterized by the 

 early "Chlamys-Hke" shell at the beaks. Interior white with a purplish hinge 

 area. Attached to rocks by the right valve. The ^2-inch long young are 

 almost impossible to separate from some species of Chlainys, except when 

 they show a mauve spot on the inside of the hinge line on each side of the 

 resilium pit, or if they show signs of distortion or a mottling pattern of 

 color on the outside of the valves. Some vouno- are bright-orancre. A common 

 species. Formerly known as H'mnites gigante7is Gray. This is a regrettable 

 name change which I have followed, since leading workers on the Pacific 

 Coast have adopted it. 



Fa77nly PROPEAMUSSIIDAE 



Genus Propeaviusshmi Gregorio 1883 



Propeavitissmm poiirtalesiaimm Dall Pourtales' Glass Scallop 



Plate 27c 



Southeast Florida and the West Indies. 



/4 inch in length. Valves very slightly convex. Shell extremely thin 

 and transparent (hke thin mica flakes). Each valve reinforced inside with 

 about 9 rod-like, opaque \\'hite ribs. Exterior of one valve is smoothish, the 

 other valve with numerous, microscopic, concentric threads. Common off- 

 shore. Frequently dredged off Aliama by amateurs. There have been a 

 number of other species described, some of which may only be forms of this 

 variable species. 



Fmjiily SPONDYLIDAE 

 Genus Spondylus Linne 1758 



Spondylus americanus Hermann Atlantic Thorny Oyster 



Plate 36b 



South half of Florida and the West Indies. 



3 to 4 inches in size. Spines 2 or less inches in length, usually standing 

 fairly erect. Color variable: white with yellow unbones, red or purple; 

 sometimes all rose, all cream or all pink. The young are much less spinose, 

 and might be confused with Chama which, however, does not have the ball- 

 and-socket type of hinge. Beautiful and large specimens are found clinging 



