174 ON NEW AND RARE BRITISH ARACHNIDA. 



C. bicolor, Blackw., are sufficiently reliable to justify their 

 separation as species it is very difficult to decide ; at present, 

 however, I am still inclined to keep them separate. 



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



An adult female sent to me from Northumberland in 

 January. 1907, by the Rev. J. E. Hull, appears to me worth 

 recording as a new species. In several respects it indicates 

 a form yet undescribed. I know of none of which it might 

 possibly be the female (not yet met with). Its leading 

 character (the formation of the genital aperture) is of a 

 very distinct and remarkable kind for a more detailed 

 description. (See post. p. 190). 



Centromerus firmus, Cambr. 



Tmeticus firmus, Cambr., Pro. Dors. F. Club. XXVI., 



p. 59, PI. A., Figs. i3a-i3c. 



An adult female received from the Rev. J. E. Hull, by 

 whom it was found in Northumberland, in 1906. 



Maro minutus, Cambr., PL A., Figs. 26-28. 



Maro minutus, Cambr., A. R. Jackson, I.e. infra, 



p. 14. PL I.V., Figs. 21-25. 



Several more examples of this exceedingly minute spider, 

 including the male, have been found near Huddersfield, by 

 Mr. W. Falconer, and an example of the latter sex has 

 bejen kindly sent to me by him (1908). The sexes are much 

 alike in general colour and appearance. 



Maro Falconerii, Jackson, PI. A., Figs. 29-33. 



Maro falconerii, Jackson, Trans. Nat. Hist. Soc. of 



Northumberland, Durham, and Newcastle-on-Tyne, 



Vol. III., Part I., p. 15, PL IV., Figs. 16-20. 



Adults of each sex of this species were found at 



Delamere, Cheshire, by Dr. A. R. Jackson, in 1907. It is 



nearly allied to J\I. minutus, and is quite as small, but the 



male may easily be distinguished by the prominent tooth in 



