BIOLOGICAL RELATIONS OF AQUATIC FORMS 195 



4. The pearl button industry. 



5. Mollusks as food. 



6. The chambered nautilus- 



7. Oyster culture. 



References 



Hunter, Essentials of Biology. Chap. XXI. 

 Elements of Biology. Chap. XXI. 



Rogers, The Shell Book. 



Many Bulletins of the U. S. Commission of Fish and Fisheries. (Write 

 to the Commission.) 



Kellogg, Shellfish Industries. 



Rogers, " Shells of the Seashore." Country Life in America, July, 

 1904. 



Moore, H. F., "Oysters and Methods of Oyster Culture." Report U. S. 

 Fish Commission, p. 23, 1897. 



Field, I. A., " Sea Mussels as Food." Bureau of Fisheries Document, 

 1910. 



PROBLEM XXXIV 



A study of how a live fish is fitted for the life it leads. 

 Materials. Small battery jars with living fish of small size, 

 such as goldfish or bream. 



a. Adaptations for Locomotion 



Observations. 1. Note the general divisions of the body 

 into head, trunk, and tail. Is there a neck ? 



2. Watch the fish carefully and see how it moves. 



3. How many paddle-like structures (fins) are there ? 



4. How many fins are in pairs ? 



5. Note. Any fins on the dorsal side of the body are called 

 dorsal fins. The fin on the tail is called the caudal fin, and the 

 median fin on the ventral side is the anal fin. The anterior 

 paired fins near the head are called pectoral fins, while those 

 about midway and ventrally located are called the pelvic fins. 



Conclusions. 1. How does a fish move forward? 



2. What are the uses of the caudal fin ? 



3- What are the particular uses of the pelvic fins ? 



