40 AXEL A. OLSSON 



Entodesma (Agriodesma) sechurana Pilsbry and Olsson . — Bayovar 



*Acanthopleura echinata (Barnes) Negritos, Yasila, Paita, Lobos de Tierra 



BIBLIOGRAPHY 



Ekman, Sven. 1853. Zoogeography of the sea. London. 



Keen, A. Myra. 1958. Sea shells of tropical West America. Stanford, Cali- 

 fornia. 

 Landes, Kenneth K. 1952. Our shrinking globe. Bull. Geol. Soc. America, 



vol. 63, No. 3, pp. 225-240. 

 Lowe, Herbert N. 1932. Shell collecting in west Central America, 



Nautilus, vol. 45, No. 3, pp. 73-82. 

 Murphy, T. C. 1925. Bird Islands of Peru. New York. 

 . 1925. Equatorial vignettes. Natural History, vol. 25, No. 5, 



pp. 431-449. 

 . 1932 Review of Gerhard Schott, 1931 "The Humboldt and Nino 



currents". Geographical Record, vol. 22, pp. 140-150. 

 . 1926. Oceanic and climatic phenomena along the west coast of South 



America during 1925. American Geographical Society, vol. 16, No. 1, 



pp. 26-54. 

 . 1936. Oceanic birds of South America. Vols. 1 and 2. Macmillan Co. 



New York. 

 Olsson, Axel, A. 1924. Notes on marine mollusks of Peru and Ecuador. 



Nautilus, vol. 37, pp. 121-131. 

 Presbrey, E. W. 1913. Collecting in Panama. Nautilus, vol. 26, No. 11, 



pp. 121-125. 

 Rost, Helen. 1955. A report on the family Arcidae (Pelecypoda). Allan 



Hancock Pacific Exped., vol. 20, No. 2, pp. 173-248, pis. 11-16. 

 Schenck, H. G., and Keen, A. M. 1936. Marine molluscan provinces of 



western North America. Proc. Amer. Philos, Soc, vol. 76, No. 6. 

 Soot-Ryen, Tron. 1955. A report on the family Mytilidae (Pelecypoda). 



Allan Hancock Pacific Expedition, vol. 20, No. 1, 174 p., 10 pis. 



PART II. PANAMIC-PACIFIC PELECYPODA 

 Phylum MOLLUSCA 

 Class PELECYPODA 



GENERAL STATEMENT 



The MoUusca as a separate branch or phylum of the Invertebrata is 

 divided into six smaller groups called Classes of which the Pelecypoda is one. 

 All members of the Pelecypoda are aquatic, living in fresh, brackish, or 

 marine waters, at all depths, and under many environmental condi- 

 tions. Of the marine sorts, the many kinds of hard-shelled clams (venerids), 

 the soft-shelled clams (myads), the mussels (mytilids), the scallops (Pec- 



