54 



THE CRAYFISH 



[CH. II 



cd 



* D 



A. Cardboard as first cut out. B. Model complete : at rest. C. Model 

 complete : muscles contracted. D. Median vertical section of 

 model to show folds. After W. E. Koth, Nature, vol. xxi. Feb. 



26th, 1880. 



For explanation of figures and letters see the text. 



Next bend the piece 1, 3, 4 upon hinge-line gk, until 

 the shaded portion is flat upon the surface of 4, where it 

 must be securely stitched; this done bend back 1, 3 on 

 hinge-line ef until 3 is at right angles to 4. The pro- 

 jecting end of 4 made prominent by these folds represents 

 the central tooth. The piece 1 must" now be bent gently 



