F. P. SMITH ON THE SPIDERS OF THE SUB-FAMILY ERIGOXINAE. 15 



I may, perhaps, be permitted to make a few remarks upon the 

 minute organs in question, especially as their arrangement has 

 been recently used as an important character in the separation 

 of some of the genera of Linyphiidae. 



Viewed with a two- thirds inch objective they appear as small 

 globular bodies, from the centre of each of which usually springs 

 a long slender bristle. The fact that these bristles are usually 

 much longer and more nearly at right angles with the leg than 

 are the ordinary hairs and spines, will help to distinguish them. 

 An increased amplification will show that the basal part of the 

 structure — which I propose to term the pocillum — is goblet- 

 shaped, and that it is to the bottom of this organ that the bristle 

 or seta is fixed. That these organs play some important part in 

 the economy of the spider I think there can be no doubt. If, 

 for example, we take a leg from a spirit-preserved specimen of 

 the very common Pachygnatha degeerii, or the larger P. clerckii, 

 treat it with boiling glycerine, mount it in Deane's medium, and 

 examine it with, say, a quarter-inch objective, we shall find, as 

 a rule, that the contents of the leg will have greatly contracted, 

 and that the only points at which an attachment with the 

 integument is maintained are at the bases of these sensory setae. 

 There is, in fact, every indication of there being an important 

 nerve connected with each of these organs, and it is, therefore, 

 only reasonable to suppose that they are capable of transmitting 

 impressions of some kind to the brain ; but as to the exact 

 nature of the sensations which they are instrumental in produc- 

 ing, there exists at present, as already stated, very considerable 

 doubt. That spiders possess the power of distinguishing aerial 

 vibrations — at any rate, to some extent — there can, I think, be 

 little doubt ; but that they have anything like an accurate 

 sense of hearing is by no means certain, although one would be 

 naturally led to this conclusion by the knowledge that many 

 species are capable of producing sounds by means of stridulating 

 organs. The fact that a spider will often exhibit no signs of 

 motion when a tuning-fork is vibrating near it, must not be 

 taken as conclusive that the creature cannot hear. Obviously, 

 it would be to the creature's advantage, even if it heard an 



