Boone, Mollusca, Cruises of "Ara" and "Alva" 313 



Distribution : This species, close congener of the West Indian 

 Area imbricata Brugiere, is widely distributed in the littoral 

 zone of the Indo-Pacific, having been reliably reported from the 

 Gulf of Suez and Red Sea southward to South Africa and east- 

 ward in the Mascarenes, through the Gulf of Manaar, Mergui 

 Archipelago, Dutch East Indies, Celebes, Kei Islands, northward 

 to Japan, down to Borneo, New Caledonia, Australia and in the 

 Society Islands. 



Material examined : Two specimens, taken in coral, Teviatoa 

 Reef, Raiatea Island, Society Islands, August 21, 1931. 



Technical description : The two Society Island specimens 

 agree well with M. Lamy's (1904) remarks and illustrations of 

 Lamarck's Area avellana. The present writer concurs in Mr. 

 Prashad's separation of A. avellana from the closely allied Area 

 imbricata Brugiere. Mr. Prashad has published an excellent 

 synonymy of the Indo-Pacific species. 



The Raiatea Island specimens are figured in plates 121 and 

 122. 



The shell is approximately oblong, ark-shape, the hinge line 

 being twice as long as the median transverse diameter of the 

 shell, the anterior end rounded, moderately tumid; the ventral 

 margin is moderately gaping, its contour having a shallow con- 

 cavity ; the posterior margin is attenuate, rather obliquely trun- 

 cate. The umbones are well separated, elevated, as shown in the 

 plates 121 and 122, for a distance equal to one-fourth of the total 

 transverse diameter of the shell at this point. There is a pro- 

 nounced blunt keel extending from the umbo diagonally to the pos- 

 terior portion of the ventral margin. The dorsal surface of the 

 shell has the anterior and median portion marked with continuous 

 series of ridges, these ridges being regularly crossed transversely 

 with moderately elevated striae. The posterior portion is also 

 ridged, the ridges approaching the keel being bluntish. The inte- 

 rior of the shell is brownish cream with some bluish tinges ante- 

 riorily. The anterior muscle scar is narrowly oval, the posterior 

 scar is the larger, more nearly circular. The hinge consists of a 

 series of rather regular, small teeth, comb-like, interlocking with 

 those alternating of the opposite valve. 



References: Area noae variety, Chemnitz, J. H. (partim) 

 Conch. Cab., 1874, p. 183, pi. 54, fig. 532. 



