Professor Pictet on the Insects found in Amber. 399 



organic remains are preserved is of great importance. The 

 insects of amber are known to us by the whole of their body, 

 and, as I have said above, their essential organs may often be 

 observed with great precision ; we may, therefore, place cer- 

 tain confidence in the results furnished by the study of them. 

 The molluscs, on the contrary, are preserved only by the shell, 

 that is to say, by an accessory part of their organism, and 

 their vital organs are known to us only by a more or less 

 questionable analogy with the existing world. Now, it is 

 principally from the molluscs that those who believe in the 

 preservation of species in many successive epochs, derive 

 their arguments. Is it not reasonable to attach more import- 

 ance to results furnished by animals most completely pre- 

 served, and consequently to consider the insects in amber as 

 furnishing a strong proof in favour of the law of specialty of 

 fossils 1 



But if the species of amber are all different from those now 

 existing, it is not necessary to conclude that the fauna of 

 these two epochs present very great differences in their gene- 

 ral physiognomy. A great number of the insects of amber 

 belong to genera now living. For some of them, it has been 

 necessary to establish new genera, and the number of such 

 as could not be classified in existing families is very limited. 



The investigations undertaken for Mr Berendt's great work 

 have hitherto detected, in the insects of this fauna, only two 

 types which are sufficiently distinct from living insects to re- 

 quire the formation of new families. These are, 1^^, The fa- 

 mily of ArchoBides in the class of Arachnides, which has been 

 established by M. Koch, and which is characterised by a head 

 united to a spliericalthorax,byfourlozenge-shaped eyes placed 

 on each side, by mandibles longer than the head, prolonged 

 like teeth, and forming long pincers. 2c//y, The family of 

 PseudO'perlides, which I have been called upon to establish 

 for very remarkable insects, which had at first been con- 

 sidered by M. Berendt as the larva of Nemoura, and which 

 have some relation in their forms with this genus, and the 

 wings wanting, or rudimentary ; but the number of joints in 

 the tarsi, the form of the antennae and that of the abdominal 



