352 ON THE ORDERS 



consist of two small feet in form of palpi, united at their 

 base, and of a lip formed of a second pair of feet dilated 

 and joined likewise together at their base. These last two 

 feet are each terminated by a strong hook, which is said 

 by Leeuwenhoeck to be pierced at the extremity for the 

 emission of a poisonous fluid activis enough to kill insects 

 instantaneously. This effect is indubitable, as an observer 

 of no less accuracy than M. Latreille has confirmed its 

 truth; but the existence of a poison in these insects as 

 well as in what are termed the mandibles of Araclmida 

 does not necessarily follow from the victim when bitten 

 being instantly paralysed. This effect may equally result 

 from these animals being endowed with an instinct which 

 leads them at once to pierce the most important part of 

 the nervous system of their prey. Nor is the existence of 

 poison proved by the mandibles being pierced, as they 

 undoubtedly are in the Chi/opoda, since the mandibles of 

 the larvae of Dytisci and other analogous insects have the 

 same structure for suction. This subject, therefore, I am 

 led to think demands further scrutiny, and the rather, be- 

 cause in those spiders I have examined it has been im- 

 possible to discover any thing more than a groove in the 

 mandibles; and because neither in the largei^t species of 

 Mygale or Scohpendra has there appeared to be any cyst 

 proper for containing poison. 



Until very lately, all known of the economy of the Chi- 

 lopoda was comprehended in the fact that they moulted in 

 the manner of Crustacea, and that Linnaeus had recorded, 

 " Scolopetidrcs pulli seu larva pedibus paucioribus instru- 

 v)itur." M. Latreille seems to have made the same ob- 

 servation ; for in the third volume of the Regne Animal he 

 expressly says of his Myriapoda, including Scolopendra 



