OF CONCHOLOGY. 



241 



ing Excursion in the Gulf of Suez during the months of 

 February and March, 1869. By Robert McAndrew. 



On the Structure of the Shell in the Pearly Nautilus. By 

 Henry- Woodward. 



Conchologia Iconica. Parts 288, 289. London, 1871. 



Ostr^a. Plates 17—27. September, 1871. 



0. subtrigona, Sowerby. Australia. 



0. retusa, Pease MSS. Sandwich Isles. 



0. quercinus, Sowerby. Hab. — ? 



0. lima, Sowerby. Sandwich Isles. 



0. lactea, Sowerby. Hab. — ? 



0. attenuate!., Sowerby. Hab. — ? 



0. palmipes, Sowerby. Philippines. 



0. reniforrais, Sowerby. Hab. — ? 



0. lentiginosa, Sowerby. Hab. — ? 



0. multiradiata, Sowerby. Hab. — ? 



0. auriculata, Sowerby. Japan. 



0. multicostata, Sowerby. Japan. 



0. lugubris, Sowerby. North America. 



0. Algoensis, Sowerby. Algoa Bay. 



0. Sandwichensis, Sowerby. Sandwich Isles. 



0. crenulifera, Sowerby. Red Sea. 



A genus like Ostr^ea affords unusual opportunities to species 

 makers, but it may be doubted whether Mr. Sowerby has dene 

 good work in describing so many new forms, in most cases, doubt- 

 less, from single specimens in collections. 



The collection of the Academy of Natural Sciences exhibits 

 in its series of Ostra>a Yirginica forms quite as distinct as many 

 of those which Mr. Sowerby has described, and it is safer to fol- 

 low the rule of only describing new forms, provided that the ma- 

 terial is abundant, conjoined with a thorough knowledge of the 

 localities and extent of variation. 



" 0. circumsutus, Gould. U. S. Expedition. Massachusetts." 

 If Mr. Sowerby had taken the trouble to consult the work he re- 

 fers to, he would have ascertained that this species inhabits the 

 Fiji and Samoa Islands. 



Leda. Plates 3 — 7. September, 1871. 



L. arcuata, Sowerby. Hab. — ? 

 L. planulata, Sowerby. Patagonia. 

 L. bicostata y Sowerby. Panama. 



