196 



C. HARTMANN. 



4. The anterior and the posterior claws vary in nearly equal 

 measure throughout, the average constancy percentage for the 

 former being 58.0, for the latter 59.75. 



5. In only one case were two individuals found that had the 

 same number of teeth on the corresponding claws of all the four 

 legs on the right side (Table II., Theridinni tepidariorum, indi- 

 viduals 2 and 4). 



In view of these facts one would be safe in saying that the 

 number of teeth on the tarsal claws of spiders is too variable to 

 be used as a specific character ; it should at least not be used in 

 a diagnosis until its absolute constancy for a given species has 

 first been demonstrated. 



In addition to this common variation in the number of teeth on 

 the claws one often meets with additional claws or with double 



rows of teeth on the same claw (mutations). Fig. I represents 

 the first foot of the seventh specimen of Theridium tepidariorum 

 in Table I. Two complete sets of claws, similar to the ones 



