SPIDBBS AND MITES. 213 



microscope, so as to make out their structure. If we 

 confine the Spider in a glass cell, it is so restless that the 

 least shock or change of position will cause it to move to 

 and fro ; and, besides, when it does become quiescent, the 

 spinnerets are closed in towards each other, so that we 

 cannot see their extremities. By selecting a specimen, 

 however, recently killed, such as this Clubkma, we may 

 discern sufficient to enable us to comprehend their con- 

 struction. 



Looking, then, at the abdomen from beneath, we see 

 the three pairs of spinnerets clustered together close to 

 the extremity. The pair most forward are shaped some- 

 what like barrels, whose free ends bend over toward each 

 other. They are covered with stiff black hairs, and just 

 within the margin of what may be called the head of the 

 barrel (for it is cut off horizontally, with a sharp rim), 

 there is a circle of very close-set, stiff, whitish bristles, 

 which arch inwards. The'whole flat surface of the " head," 

 within this circle of bristles, is beset with very minute 

 horny tubes, standing erect, which are the outlets of the 

 silk- ducts that belong to this pair. 



Behind this first pair are seen the middle pair, almost 

 concealed, however, from their shortness and smallness, 

 and from the approximation of the first and third pairs. 

 We can discern that they are more teat-like than the pre- 

 ceding, terminating in a minute wart, which is prolonged 

 into a horny tube. The whole teat is set with similar 

 tubes, which are larger and longer than those of the first 

 pair. Finally, the third pair resemble palpi, for each con- 

 sists of two lengthened joints, and are bluntly pointed. 

 The spinning tubes in these are limited, as it appears to 

 me, to one or two at the extreme end of each spinneret, 

 the whole surface besides being covered with the ordinary 

 long bristles. Strictly speaking, however, they are three- 

 jointed, for all the spinnerets spring from wart-like sockets, 

 which may be considered as basal joints ; and as the 



