66 THE MOUTH-PARTS. 



verge to meet one another at the base as at tlie apex. 

 At the former, however, they enclose a space which 

 has the form of an acute triangle, while at the basal 

 end they curve round to meet one another. At the 

 base the chitine is rounded off on the outer side, but is 

 produced into a sharp point on the inner edge. 



The palpi (PI. LXIV, fig. 6) are short, 1 -jointed, 

 rounded, but not tapering at the free end, and with 

 two longish setse and one or two minute hairs, none 

 of them, however, attached at the apex. 



The second pair of maxilla3 are membranous and 

 delicate. PI. LXIV, fig. 7, represents their form in 

 Tomocerus ; in Smijntkuriis they have at the extremity 

 two teeth of equal size, on the basal side of these are 

 three more or less projecting lobes, and then follow a 

 number of small teeth, which end at a point where the 

 two maxillae converge towards the middle line so as to 

 touch one another. They are closely attached to the 

 ligula (PI. LXIV, fig. 3), which is membranous and 

 very delicate. 



The under lip (PI. LXIV, fig. 5) is stronger, and 

 consists of two more or less quadrate lobes. 



It must be observed, however, that the mouth of the 

 Lipurce is not mandibulated. Meinert's ^ description of 

 the mouth parts is substantially similar, but the organs 

 which I had considered as the second pair of maxillge 

 he regards as labial palpi. He lays just stress on the 

 importance of the characters afforded by the mouth 

 parts with reference to the true position of Poclura and 

 its allies. While agreeing with Lepisma and the 

 mandibulated series of insects in the possession of 

 true mandibles, the Collembola differ from them in the 

 important point that, instead of being external, their 

 mandibles and maxillge are retracted within the cavity 

 of the skull. In some respects, therefore, they are 

 intermediate between the mandibulate and haustellate 

 insects. 



' ' Naturliistorisk Tidsskrift,' ser. 3, vol. iii, p. 400, Copenliageu, 

 1865 ; and ' Ann. and Mag. Nat. His.,' 1867, p. 361. 



