new Geni'rn and Speciea of Jjriti.sh Spi'lers. 97 



" Herewith I return Mr. Morisou's letter and the two iniuutc 

 spiders . . . After a careful examination I am inclined to 

 believe they constitute a variety of Neriene errans^ the palpi 

 and palpal organs of the male being perfectly identical in 

 structure with tiiose of that species." 



In another letter of February 27th he says : " The Neriene 

 from the Durham collieries differs from N. errans, as you 

 remark, in the colour and markings of the abdomen, .... 

 I hope you may be able to satisfy yourself that it is a 

 distinct species, .... and will speedily publish a descrip- 

 tion of it, for its habitat and economy arc certainly very 

 remarkable." 



Later, under the date of March 6th, speaking of the same 

 spiders, lie says : ". . . which I entirely concur with you in 

 regarding as constituting a variety of Neriene errans, the 

 slight difference in colour being caused in all probability, as 

 you remark, by the influence of the remarkable situation in 

 which they are found." 



It is very evident from this interesting correspondence 

 that Dr. Meade tried hard to find some structural difference 

 between the specimens obtained in the colliery and those 

 named previously errans by Mr. Blackwall ; and thus it 

 happens that the former were placed in a separate tube, both 

 as a " variety of errans " and also as " occurring in coal- 

 pits." 



But it now also happens that the two species which are 

 evident amongst Mr. (Jampbell's specimens of errans and 

 those of the Jiev. O. P. Cambridge correspond exactly with 

 these two varieties, and, further, that I have myself found a 

 distinguishing character which Dr. Meade might have con- 

 sidered a sufficient one to found a species on had he happened 

 to notice it. I feel myself justified, tlien, in describing this 

 form " from coal-pits," and those identical with them from 

 the other collections, as a distinct species ; while it follows of 

 necessity that the others are the original errans, Bl. ; for it 

 may be further noted that these others are also identical with 

 the four females constituting the only surviving type speci- 

 mens of Mr. Blackwall's errans. 



The following analysis will present the conclusion more 

 clearly : — 



Ann. c^; Mag. K Hist. Ser. 6. Vol. xiii. 7 



