184 Prof. J. C. Schjbdte on the Classification of Curaoibyces, 



into play, without fail or delay, whenever they are wanted. This 

 contrivance consists in the peculiar position of the claw-joint, 

 its articular insertion being effected on a higher plane than that 

 of the other joints, whereby the animal is enabled, at its option, 

 to raise the claws whilst walking or running, or suddenly to 

 drop them and, as it were, cast anchor. Besides, in order to 

 diminish the weight of the claw-joint when raised up, its point 

 of insertion is removed a little upwards, so as to be actually on 

 the upper surface of the tarsus, the joint which carries it being 

 also cloven, partly in order to enable the animal to bring the 

 foot-pads of that joint to a level with those of the first joints of 

 the tarsus, partly in order to afford space for the movements of 

 the claw-joint. 



However, something more is evidently necessary in order to make 

 this mechanism work with perfect ease. Without some further 

 contrivance, the position of the claw-joint, when raised up, would 

 become stiff and straddling; and when turned in different direc- 

 tions, its base would always be exposed to getting foul of the 

 upper parts of the lobes of the cloven joint, between which it 

 lies. The reader may realize the arrangement by keeping the 

 first and second finger extended in such a position that they di- 

 verge as much as possible, and then imagining that they represent 

 the two lobes of the cloven joint, and that the long claw-joint, 

 furnished with two moveable claws, is implanted in the middle 

 of the slanting surface in the cleft between the two fingers. It 

 will thus easily be understood that all difficulties and impediments 

 to the necessary freedom and delicacy of the movement may be 

 surmounted by inserting a small new piece between the base of 

 the claw-joint and the point of insertion at the bottom of the 

 cleft between the two lobes. This is in reality the expedient 

 chosen ; and the nodule observable at the base of the claw-joint is 

 the real penultimate joint of the tarsus, altered to such a degree 

 in size and shape, for the purpose indicated, that many authors 

 entirely disregard it in counting the joints of the tarsus, and 

 describe the large cloven joint as the penultimate, although it 

 is in reality the third from the end. 



That this modification of the penultimate joint in the so-called 

 pseudo- or sub-pentamerous and -tetramerous feet has hitherto 

 been considered enigmatical* is principally owing to the authors 



* One of the most learned and thinking entomologists of the present 

 day, who, besides, has made a special and comprehensive study of the 

 Chrysomelidce, describes the reduction of the penultimate joint as " une 

 particularite dont l'explication est impossible dans l'etat actuel de nos 

 comiaissances, et qui ne le sera probablement pas moins quand nous aurons 

 pe'netre plus avant daus l'organisation de ces insectes.. .. II est d'autant 

 plus difficile dc se rendre comptc d'un caractere commun a un aussi 



