LONG-TAILED GROUP 



3235 



leave her until able to shift for themselves. Growth, however, although fast at first 

 is a slow process, the crawfish not reaching maturity until about five years after 

 birth. They probably live under favorable conditions for about fifteen or twenty 

 years. Although not considered a delicacy in England, on the Continent and 

 especially in France, they are much appreciated. It is said that in Paris alone from 

 five to six million crawfish are consumed annually, and to meet the demand large 

 numbers are imported from Germany and elsewhere, and artificial cultivation has 

 been carried on with success. The crawfish belonging to this family are found in 

 the Northern Hemisphere; but in the Southern Hemisphere several forms occur 

 which are referred to another family, Parastaddce , differing in the arrangement of 

 the gills. Some of these forms are of large size, the Tasmanian Astacopsis franklini 

 measuring a foot or more in length. 



The next tribe, Caridea, embraces the shrimps and prawns, in which the last 

 three pairs of thoracic limbs are never chelate, although the two pairs in front of 



WEST-INDIAN PRAWN, Atyd. 



(Natural size.) 



them are frequently so. The tribe is divided into three sections. The first of these, 

 or Crangoninea, contains the family Crangonidce or shrimps, characterized by hav- 

 ing the first pair of trunk limbs subchelate, that is, with the terminal segment 

 capable of being folded back upon the penultimate. The common shrimp ( Crangon 

 vulgaris) occurs in shallow water on sandy coasts of temperate countries of the 

 Northern Hemisphere. Its color is a speckled gray, corresponding closely with 

 that of the sandy sea bottom upon which it lives, and in which it buries itself when 

 threatened with danger. To escape the vigilance of fish, shrimps resolutely keep 

 themselves hidden during the day, but come forth at night to hunt for food. The 

 presence of this they perceive by means of scent, since a blind shrimp will find food 

 as quickly as at, uninjured one. A second British species is Allman's shrimp 

 (Crangon allmam), abundant in deep water in the Irish Sea and on the west 

 coast of Scotland. It may be at once distinguished by the presence of two fine 

 keels on the upper side of the sixth segment of the abdomen. Both have a short 



