O- YI. 



THE TESTIS AND ITS SECRETION IN THE 

 DEOAPODOUS CRUSTACEANS. 



The organs of generation in the male crustacean consist of 

 testes, vasa deferentia, and external or intromittent organs. 



In no class of animals do these parts vary so much as in that 

 now under consideration. In every family, and almost in every 

 genus, they afford generic, and in some even specific characters. 

 This variableness of configuration and structure is not peculiar 

 to the organs of reproduction, but exists also in the other systems 

 the vascular and respiratory, the nervous and locomotive. 

 Such a variableness is to be looked for in a class, the forms in 

 which pass from that of the annelids, through the articulata, to 

 the mollusk. Throughout all this range of form the organs 

 and functions vary in accordance with those in the group of 

 animals to which the crustaceans presenting them are analogous. 



In all the higher, or brachyurous crustaceans, the internal 

 organs of generation are comparatively most highly developed. 

 These organs exhibit the greatest complexity of form and struc- 

 ture among the Triangulares, but in the next order, the Cyclo- 

 metopa, they are of great size. These crustaceans are accord- 

 ingly the most prolific, and in greatest demand as articles of diet. 

 The Catometopa, or rather the higher forms of that family, have 

 these organs also very large; this family containing the land-crabs 

 of tropical climates, which are used as food. 



