50 



NATURAL HISTORY OF ARTHROPODS. 



which is frequently found in that beauti- 

 ful sponge from the Philippines {JE^uplec- 

 tella); which has received the name of 

 "Venus' flower-basket." It was formerly 

 supposed that these small shrimps were in- 

 serted in the sponge, and the opening then 

 skilfully closed by those ingenious people 

 of the East to whom we owe so many 

 " curios," from mermaids to curious carved 

 balls of ivory, one within the other. Such, 

 however, is not the case. Not only has no 

 one yet been able to discover the openings 

 which would be necessary for such an 

 operation, but every specimen thus im- 

 prisoned belongs to the same species, — 

 a fact which would hardly be probable 

 were we indebted to man for the arrange- 

 ment. 



The next grouj) in order is the 

 CARIDEA, which is represented in all 

 seas by many species, some also occurring • 

 in fresh water. In North America alone, 

 including the West Indies, about one hun- 

 dred distinct forms occur. In these forms 

 the antennae have a large basal scale, the 

 carapax is not joined at its inferior margin 

 to the mandibular and anteunal segments, 

 while at the most only the two anterior 

 pairs of thoracic feet terminate in a pincer, 

 while frequently but a single pair (either 

 the first or second) has such a termination. 

 In Nika an interesting modification takes 

 place, — only one foot of the anterior pair 

 is chelate, the other being monodactylous. 

 Another feature, which is common to many 

 genera, is the breaking up of the carpal 

 (antipenultimate) joint of one pair of legs 

 into a long series of annuli, affording great 

 freedom of motion, though the pincers 

 borne on these feet are always so small 

 as to render it diflicult to see what can 

 be the gain to the animal by this struc- 

 ture. 



In the eastern United States the 



Fig. 59. — iiici/er (natural size, J of ail inch in length). r\ -3 i!i,iTii •• 



•' ^ Candea are of but slight economic im- 



portance, but in other parts of the world, under the names of shrimps and prawns 

 ■(German Gameelen, French crevette), they are largely used as an article of food. 

 The shrimp of England is the Crangon vulgaris of science, while the term prawn 



