TEETH ON CLAWS OF ADULT SPIDERS. 



193 



TABLE I. FEMALES. Continued. 



covered, placed under the compound microscope and pressure 

 applied until all the teeth came into full view. 



The results of the counting of the teeth are recorded in the 

 accompanying tables, Table I. containing the figures for the fe- 

 males and Table II. for the males. The three claws were always 

 distinguished from one another and the number of teeth on each 



recorded after the formula ----- , where represents the number 



of teeth on the anterior, / on the posterior and z on the inferior 

 claw. 



The reduction in the number of teeth seems to take place at 

 the proximal end of the claw because, firstly, the distal teeth 

 usually maintain the size and form characteristic of the species, 

 and secondly because the proximal tooth (or teeth) in some cases 

 becomes so small as to merit the name tubercle in place of 

 tooth. This latter fact forced me to establish a criterion to de- 

 termine what to count as a tooth and I decided to call the 

 structure a tooth if it had attained a length at least half as great 

 as its width at the base.. In Dictyna volupis the two distal teeth 

 are small and are closely approximated to the claw for nearly 

 their entire length. One of these was counted in some four or 

 five cases where it was unusually large and stood out from the 

 claw for at least half its length. 



In order to reduce the tables to percentages so as to get at a 

 simple set of figures for comparison I have adopted what may 

 be called the " percentage of constancy " method, which may be 

 illustrated as follows : 



In Table I. the anterior claw of the first leg of Lycosa nidicola 



