72 Journal New York Entomological Society, ["^"o^- ^i^. 



1. In size the individuals range from the minimum length of 2.10 

 mm. to the maximum length of 3.00 mm. 



2. In color we have variations from forms with very dark, almost 

 black pedipalps and cephalothorax, to those with light yellowish 

 brown pedipalps and cephalothorax. 



3. The shape of the movable digit of the chelicera varies from a 

 rather short, markedly curved form to one much longer and with the 

 external margin almost straight. 



4. There is a great variation in the size and number of the tuber- 

 cles found on the dorsal surface of the cephalothorax and on the 

 basal segments of the pedipalps. In the females of some collections 

 these are practically absent, but in the well developed males of other 

 collections they may number a score or more and are quite prominent 

 (see PI. II, Figs. 2, 3). 



5. The lateral, posteriorly directed spurs of the abdominal scuta, 

 found only in the case of the males vary greatly in number and size 

 (see PI. II, Figs. 6, 7, 8). 



Adaptation of \' ariations. 



After making a careful study of the data given in these pages 

 concerning the variations of this species, and the data collected by 

 other writers, I have found the following adaptations of variation 

 which may be confirmed by examining the data cited and the figures 

 given on Plates I and II : 



C. cancroidcs varies according to two prime factors; first, in 

 regard to the situations in which it is found, and second, in regard 

 to its geographical distribution. 



In regard to situation the factors of nourishment and of mechan- 

 ical adjustment to the conditions appear to be of great importance. 

 Thus it is found that individuals (varieties) found under bark differ 

 from those found in association with man and his various habita- 

 tions in that they arc much smaller, more flattened, have fewer and 

 smaller tubercular processes on the cephalothorax and pedipalps, and 

 have smaller chelicer?e, with the movable digit more curved. This 

 has, perhaps, resulted from a change in the kind of the food eaten. 

 The size of those species found under bark is restricted greatly be- 

 cause they are compelled to move about in very narrow spaces, on the 



