138 DR. A. RANDELL JACKSON ON THE 



I believe the female described in 1910 (sub passiva) is the 

 true partner of the typical A. cauta, as it occurs freely with 

 the males of that species in unmixed collections sent to me 

 from Yorkshire by Mr. Falconer, and has also occurred with 

 males of A. cauta taken in other localities. 



A. cauta Camb. almost exactly resembles A. subtilis Camb. 

 in size, colour, and facies. It can, however, be separated by 

 the structure of the sexual organs. 



The lamella characteristica is very distinctive; it forms in 

 front a sort of comb beset with very numerous short teeth. 

 The exact number of these teeth varies, but I have never seen 

 a specimen of which there was the slightest doubt. 



On the inner side of the palpal tarsus near the base, and 

 close to the dorsal surface, there is a process similar to that of 

 A. subtilis. In the present species, however, it is much larger, 

 and dilated at the extremity. It can easily be seen from the 

 external side of the palpus rising over the dorsal surface of 

 the tarsus near the base (see 5e). 



The epigyne is usually larger and darker than that of A. 

 subtilis Camb., and the central process is very deeply cleft at 

 the extremity. There is probably some variation in this 

 respect, but typical examples are very easily recognized. 



The shape of the cephalothorax provides no trustworthy 

 information as to the identity of this species. 



The female palpi are always tumid in the specimens I have 

 seen. All that I have examined have been very similar in 

 the breadth of the terminal joints, which measured about 

 •18 mm. on the transverse diameter of the upper surface. 

 Slight variation was frequently seen, but not the gross 

 differences noted in A. subtilis. 



A. cauta Camb. has occurred pretty freely in Northumber- 

 land, Cumberland, Yorkshire, and Cheshire. It appears rare 

 in the South, but the typical male was found in the moun- 

 tainous districts of Glamorganshire. It may be found in 

 company with A. subtilis Camb., but is common amongst 



