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VENUS, YOLDIA 133 



Make drawings of sections that pass through the heart 

 and through the posterior adductor muscle. 



Belding: A Report upon the Quahog and Oyster Fisheries of Massa- 

 chusetts. Fish and Game Com., Mass., 1912. 



Howard and Anson: Phases in the Parasitism of the Unionidae. Jour. 

 Parasitology, 9, 1922. 



Lefevre and Curtis: Studies on the Reproduction and Artificial Propa- 

 gation of Fresh-water Mussels. Bull. U. S. Bur. Fish., 30, 1910. 



Mathews: The Palps of Lamellibranchs as Autonomous Organs. Jour. 

 Exp. Zool., 51, 1928. 



Nelson: On the Origin, Nature, and Function of the Crystalline Style 

 of Lamellibranchs. Jour. Morph., 31, 1918. 



: Recent Contributions to the Knowledge of the Crystalline Style 



of Lamellibranchs. Biol. Bull., 49, 1925. 



Smith: The Mussel Fishery and Pearl-button Industry of the Missis- 

 sippi River. Bull. U. S. Fish Com., 1898. 



If time permits, it will be desirable to become acquainted 

 with some of the structures of theoretic importance and with 

 some of the adaptations of pelecypods for the lives they live. 

 For this purpose a few forms have been selected, and direc- 

 tions for the study of the particular parts in question are 

 given. 



YOLDIA LIMATULA 



This form belongs to the order Protobranchia, and is sup- 

 posed to be one of the most primitive of living pelecypods. 

 It lives in soft mud, such as is found in quiet coves and bays. 

 (It is abundant in the Eel Pond at Woods Hole.) Although 

 it burrows in the mud, it lives near the surface, and fre- 

 quently has the posterior end above the mud. 



1. Place a specimen in a dish of sea water, and notice 

 the movements and shape of the foot. See if the movements 

 are always alike. What would happen if such movements 

 were made by a specimen lying on soft mud? Place a speci- 

 men on mud and watch the results. 



2. Leave a specimen in an aquarium in which two inches 

 of bottom mud has been placed, and see if it is feeding in the 

 morning. 



3. Place a young, transparent specimen in a watch glass 



