THE CATCH. 69 



No one, indeed, who lias watched the habits of the 

 CoLLEMBOLA, Can cloubt its function. 



If a Smynthurus is laid on its back — a position from 

 which it has some difficulty in recovering its feet — and 

 if, while it is in this attitude, a piece of glass is brought 

 within its reach, the animal will endeavour to seize it 

 with the feet, but at the same time it w411 project one 

 or both of the ventral tentacles and apply it, or them, 

 firmly to the glass, emitting at the same time a drop 

 of fluid, which, no doubt, gives a better hold. In the 

 parallel case of the Poduridce, M. I'Abbe Bourlet sup- 

 poses that the ventral tube acts as follows : — " 1°- qu'il 

 sert a ces insectes a se maintenir sur les surfaces per- 

 pendiculaires en y faisant le vide ; 2°- que le liquide 

 excrete par lui sert a humecter la queue et la rainure ; 

 3°" qu'il supplee a la faiblesse des pattes dans les chutes 

 qui suivent les sauts." I am therefore disposed to 

 agree with him in so far as he denies that the adhesive 

 power depends altogether on the viscous fluid ; but, 

 on the other hand, I cannot attach much importance 

 to his two latter suggestions. De Geer well under- 

 stood the use of this curious organ. He says, " Quand 

 la Podure [under which name he includes the present 

 genus Smynthurus'] marchait centre les parois du 

 poudrier, il lui arrivait souvent de glisser ; c'etait comme 

 si les pieds lui manquaient, de facon qu'elle etait sur 

 le point de tomber; dans I'instant memo, les deux 

 filets parurent et furent lances avec rapidite hors de 

 leur etui, s'attachant dans le moment au verre par la 

 matiere gluante dont ils sent enduits, en sorte qu'alors 

 la Podure se trouvait comme suspendue a ces deux 

 filets." Nicolet gives a similar explanation of their 

 function, and, like De Geer, attributes the adhesive- 

 ness to the glutinous matter which they secrete. 



The next abdominal appendage is the " catch " (PL 

 LVII X, PI. LVIII E, and Pis. LIX and LX). As will 

 be seen by the latter figures, it is in Tomocerus situated 

 on the ventral side of the third abdominal seg;'ment. 

 It is described by Nicolet as " une petite piece blanche, 



