156 ARTHROPODA. 



attached to the sides of the base of the abdomen. The female 

 has two of the abdominal segments fused. In the male the seg- 

 ments are free. 



A drawing of the specimen is desirable. 



Sharper Notes on the Marine Copepods and Cladocera of Woods Hole and 

 Adjacent Regions, Including a Synopsis of the Genera of the Harpocti- 

 coida. Proc. U. S. Nat. Mus., 38, 1910. 



Wheeler: Free-Swimming Copepods of the Woods Hole Region. Bui. 

 U. S. Fish Com., 19, 1899. 



ARGULUS. (Fish-Louse.) 



These animals may be found on many species of fresh-water 

 and marine fish. Notice their shape and determine how they 

 cling to their host. Are they able to crawl? Can they swim? 



1. Into what regions can the body be divided? 



2. Examine the appendages and find: . %< 



(a) The eyes, the eye-spot, and the two pairs of small 

 antennce. 



(b) The sucking proboscis, composed of mandibles and max- 

 illce, which lies between the suckers. 



(c) The suckers, which are the modified second maxillce. 



(d) The posterior (third) maxillipeds just behind the suckers. 



(e) Four pairs of biramous thoracic appendages. What is 

 their function? 



Make a drawing of the animal. 



Wilson: The Fish Parasites of the Genus Argulus Found in the Woods Hole 

 Region. Bui. U. S. Bur. Fish., 24, 1904. 



LEPAS. (Goose-Barnacle.) 



If possible, examine a cluster of specimens as they naturally 

 occur attached to floating timber. 



1. Why are the peduncles much larger in some specimens 

 than in others? Are they contractile so the body may be moved 

 into different positions? Would such movements be of value? 



2. Notice the thoracic appendages. Can they be thrust 

 from the shell? What is their character? What are their char- 

 acteristic movements? Drop a small piece of clam meat on 



