ADJUSTMENT OF ORGANISMS TO ENVIRONMENT 421 



Separate out the species in suitable receptacles for keep- 

 ing alive. Remember that all are carnivorous, and that the 

 larger ones if pressed by hunger may eat the smaller; 

 remember also that all can climb and fly, and cover vessels 

 accordingly. 



The record of this study may consist in a diagram on the 

 plan of the left hand side of fig. 224 on page 385, with the 

 names and places of all diving beetles collected indicated 

 therein. 



Study j8. The adaptive structures of diving beetles. 



Materials needed: Preserved specimens of the same 

 species used in the preceding study. 



Study these species one by one, and record the more 

 obvious characters called for in a table prepared with the 

 following column headings : 



Name. 



Sculpture (development of furrows or structural ornamen- 

 tation, especially of the back). 



Vesture (development of hair on the body, especially oi 

 the back). 



Scutellum (visible or hidden). 

 Femur: | 



Relative length <J Tibia: } expressed in ratio /:x:y 

 Tarsus. ) 



I On what legs developed 

 Specialized swimming fringes ( Relative excellence 



| Number (one or two) 

 Claws < Equality (equal or unequal) 



{ Mobility (fixed or movable) 



Special braces (such as the lobe, x, of the femur, shown 

 in figure 171 on page 285, which serves to steady the 

 action of the tibia, and to keep it moving in one plane: 

 developed where on legs). 



