MR. LUBBOCK ON THE THYSANURA. 447 



tentacles, and apply it or tliem firmly to the glass, emitting at the same time a drop of fluid, 

 which no doubt gives a better hold. I have, however, known a Smynthuriis seize hold with 

 one of its tentacles of the needle with which I was tui-ning it over on its back ; and the 

 adherence was much firmer than the mere presence of a little fluid would account for. 

 In the parallel case of the Poduridse, M. I'Abbe Bourlet supposes that the ventral tube 

 acts as follows : — " 1°. Qu'il sert a ces insectes a se maintenir sur les surfaces perpendi- 

 culaires en y faisant le vide ; 2°. Que le liquide excreta 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 understood the use of this curious organ. He says, " quand la Podure 

 (under which name he includes the present genus Smyntlmrus) marchait contre les 

 parois du poudrier, il lui arrivait souvent de glisser ; c'etait comme si les pieds lui man- 

 quaient, de fagon qu'elle etait sur le point de tomber ; dans I'instant meme, 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 sont 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 adhesiveness to the glutinous matter which they secrete. 

 Upon this point, however, I feel compelled, as already mentioned, partly to disagree with 

 these two high authorities. 



The Nervous System. — M. Nicolet describes the nervous system of Smynthurus as con- 

 sisting of four ganglia, with a double connecting-cord. Two of these ganglia occupy the 

 head, and form the oesophageal collar. The 1st suboesophageal ganglion (Nicolet, I. c. 

 pi. 4. fig. 1 c) gives off two small nerves on each side. The 2nd, which is situated nearly 

 midway between the 1st and 3rd, has a third nerve on each side ; and the posterior 

 ganglion, besides three pairs of nerves corresponding apparently to those of the pre- 

 ceding ganglion, has at its hinder extremity three other much larger nerves, which 

 supply the posterior part of the body. 



I found much difficulty in making out the nervous system at aU, but hoped that Dr. 

 Hicks' s bleaching process might facilitate the matter. In this, however, I was disappointed, 

 nor was Dr. Hicks himself more successful : he writes me word, " I have been as unsuc- 

 cessful as you in the bleaching process. The thickness of the body, and the want of 

 thickness of the chitine layer allowing shrivelKng, are obstacles which I am afraid will 

 not be overcome. It does well for the legs, wings, and antermse ; but for the thick bodies 

 it seldom, I thinlc, will suit, unless the integument is very firm." Dr. Hicks, however, 

 satisfied himself that there were " three thoracic ganglia, with a posterior cord extending 

 into the abdomen in the median line." 



Since that time I have been unable to obtain any specimens of S. Buskii, which, 

 being a large species, is a favourable subject for examination. I had, however, already 

 satisfied myself of the presence of two large ganglia in the anterior part of the body ; 

 but the nerves proceeding from them seemed to me to be larger than those figured 

 by Nicolet. 



VOL. XXIII. 3 P 



