44 CRUSTACEA 



(4) Organs of Sensation (Feeling). 



(a) Location? 



(b) Consist of what? 



(c) Use? 



(5) Upon what sense does the crayfish most rely? Why? 

 For comparison, make a study of any other crustaceans 



available, using the General Studies and the Morphophysio- 

 logic Study for the crayfish, making any necessary changes or 

 omissions. 



MOUNTING A CRAYFISH 



Take a smooth pine board about 6x8 inches or larger, as 

 the size of specimen requires. (Heavy cardboard, as suggested 

 by Colton, will answer if boards are not available.) Bore a 

 small hole in the center of one end of the board if you wish to 

 hang up your specimen when mounted. 



1. Draw a line the length of your crayfish down the center 

 of the board. 



2. Take a moist (not wet) crayfish, and very carefully 

 remove and arrange in their natural order the following ap- 

 pendages from one side of the crayfish: One antennule, one 

 antenna, one mandible, one metastoma, two maxillse, three 

 maxillipeds, five legs, and six swimmerets. 



3. Temporarily pin your specimen so that the center of it 

 from beak to telson will be over the line drawn in the center of 

 the board, and so that the appendages not yet removed will lie 

 in their natural position. 



Now take the appendages you have removed, one at a time, 

 beginning anteriorly, and with a small amount of Major's 

 white cement stick each one to the board so that it lies as 

 nearly as possible in the same position as the one not yet 

 removed, except that instead of overlapping, the mouth-parts 

 should lie one in front of another so as to show all the parts, 

 and the legs and swimmerets should have their bases along the 

 sides of the body and not under it. 



When these are securely fastened down to the board, unpin 

 the crayfish and remove the appendages from the other side, 

 arranging them similarly on the other side of the central line 

 and at the same distance from it. 



