THE LOBSTER AS A TYPE OF CRUSTACEA 27 



ences in the form of the first two pairs of swimmerets. 

 In the female the first pair, which have only one 

 branch, are short and slender filaments, while in 

 the male they are stout and peculiarly twisted rods. 

 The second pair in the female are similar in form to 

 the succeeding pairs, but in the male they have an 

 additional lobe on the inner branch. The openings 

 of the generative organs will be found in the male 

 on the basal segments of the last pair of legs, while 

 in the female they occupy the same position on the 

 legs of the last pair but two. The testis of the male 

 lies in the thorax, just below the heart. The ovary, 

 which has the same position in the female, is usually 

 much more conspicuous, and from its red colour in 

 the cooked lobster it is known as the " coral." On 

 the under-side of the thorax of the female, between 

 the last two pairs of legs, is a three-lobed structure 

 enclosing a cavity known as the "sperm-receptacle." 

 Its function is to receive the fertilizing substance 

 from the male, and to retain it until the eggs are 

 ready to be deposited. 



In the Lobster, as in many other Crustacea, the 

 eggs are carried by the female until they hatch. 

 After being extruded from the oviducts, they are 

 attached by a kind of cementing substance to the 

 swimmerets, where they hang in bunches. The 

 swimmerets are kept constantly moving, so that the 

 eggs may obtain the oxygen necessary for the de- 

 veloping embryos within. A female Lobster carrying 



