324: F. P. SMITH ON SOME BRITISH SPIDERS TAKEN IN 1908. 



characters which the author regards as specific. The arrange- 

 ment of the eyes, their relative size, and their distance from 

 the frontal margin of the caput are all characters which I find 

 particularly unstable in this genus. The form of the abdomen, 

 its colour, and the size of the entire spider are also character- 

 istics which cannot be implicitly trusted for purposes of specific 

 differentiation. I have on more than one occasion met with 

 male specimens typically microphthalmum as far as actual struc- 

 ture was concerned, but with the exception that the entire 

 spider, including the palpi, was much below the normal size. 

 Such forms ought probably to be regarded as dwarfed varieties 

 rather than as true species, on exactly the same lines as 

 Gnaphosa lapidosa var. macer. Until, however, a far larger 

 amount of material than is at present available can be 

 examined, I do not consider it advisable to make any definite 

 alterations in the existing list of admitted Porrhommae, and 

 must content myself with remarking that, to my mind, both 

 P. oblongum and P. campbellii are, as species, extremely weakly 

 defined from P. microphthalmum,. 



The small size of the eyes in this genus, and more particularly 

 their often imperfect structure, is a matter which may be worthy 

 of a few remarks. Many of the earliest examples described were 

 found in caves and coal-mines, and it was promptly suggested 

 that the diminished eyes were due to the influence of the dark- 

 ness of the creatures' habitat. However true this may be in the 

 matter of caves of considerable geological antiquity, it hardly 

 seems to apply in the case of coal-mines. Besides, specimens 

 taken in meadows near London possess eyes hardly, if at all, 

 larger than the types from the Durham mines. The origin of 

 the spiders in coal-mines is not absolutely certain, but it seems 

 reasonable to suppose that they have been introduced in the 

 horses' fodder. An examination of this commodity, before it is 

 taken down the shaft, will convince one that a very large 

 number of small spiders and insects are concealed in the bundles. 

 Once in the bowels of the earth, and cut off from the normal 

 food supply, the struggle for existence amongst these creatures 

 must be exceedingly keen, and it requires a very small stretch of 

 the imagination to suggest that those species normally possessed 

 of imperfect eyes would more easily adapt themselves to the 

 altered condition than their comrades with well-formed optical 



