HARD PARTS OF THE COMMON CRAB. 177 



(i.) The first pereiopod is much larger and stronger than 

 any of the others, with serrations along its anterior edge, 

 and the tip is colored bright blue in the male, and red in 

 the female. The distal end of the propodite is prolonged 

 forwards as a finger-like process, which, lying parallel to 

 the dactylopodite, forms the chela, or claw. The opposed 

 edges of the halves of the claw are set with tooth-like 

 serrations, and these are round and blunt in one claw, 

 sharp and pointed in the other. 



(ii.) The second, third, and fourth pereiopods are 

 very like each other, shorter than the first, and without 

 chelse. 



( iii. ) The fifth pereiopod has its terminal joints flattened, 

 and fringed with hairs, and is a paddle-shaped swimming 

 organ. 



(iv. ) On the inner ventral edge of the coxopodite of the 

 fifth pereiopod of the male, notice a delicate membraneous 

 tube, the projecting tip of the vas deferens. It passes 

 into the base of the first abdominal appendage. 



i. The female reproductive orifices are covered by the 

 abdomen, and are near the middle line on the sternum of 

 the somite which carries the third pair of pereiopods. 



j. In front of the coxopodite of the first pereiopod, 

 notice a large aperture through which the water passes to 

 the gills. Move the third maxilliped, and notice that its 

 flabellum runs backwards and outwards from the protopo- 

 dite into this cavity. 



k. Outside and anterior to the bases of the appendages, 

 the outline of the body is completed by the reflected ven- 

 tral portion of the carapace, on the anterior margin of 

 which are the eyes, the antennules, and the antennae. 



I. Make a drawing of the ventral aspect, showing all 

 these points. 



