190 ON NEW AND RARE BRITISH ARACHNIDA. 



encircles the spinners on the under side ; the ventral scutum also 

 includes the spiracular plates and extends to the fore-extremity 

 of the abdomen, where it ends in a short rugulose collar receiving 

 the connecting pedicle. The colour of both the dorsal and 

 ventral scutum is like that of the cephalothorax, those parts 

 not covered by the scuta being dull whitish ; the whole is 

 furnished thinly with fine hairs. 



The female resembles the male in size, colour, and general 

 appearance. The genital aperture appears to consist simply in 

 a transverse slit marked by a dark yellow-brown marginal line, at 

 the middle of which there is a very slight, narrow, transverse 

 opening. 



Both sexes of this very interesting little spider were found and 

 kindly sent to me from a hothouse in the Kew Gardens on the 

 1 3th of February, 1908, by Mr. Horace Donisthorpe. Their 

 domicile is among cinders, underneath flower pots on the floor. 

 In company with the spiders were examples of a small West- 

 Indian Ant (Wasmannia auropunctata, Roger), of nearly similar 

 length and colouring, and remarkably like the spider in general 

 appearance. Whether the ant had been imported along with 

 the spider, or whether the habitation of the one beneath the 

 flower pot had taken place before the arrival of the other, are 

 conjectural facts on which we have no evidence. If found 

 together in a natural state one would conclude that a protective 

 resemblance was pointed to by their similar appearance ; but 

 whichever might be the one benefitted by this resemblance, it 

 can hardly have been arrived at during their sojourn in a Kew 

 hothouse. Perhaps some entomologist, if there be one, 

 acquainted with the ant in its native country, might know of 

 facts bearing on the point. 



Centromerus probabilis, sp. n. PL A., Figs. 20-23. 



Adult female, length 2^ lines. 



The general form and aspect of this spider is of the ordinary 

 kind. 



