68 GEOLOGICAL MEMOIRS. 



but apparently insists that the former also were deposited as drift- 

 wood in the locality where they are found, and became mineralized 

 subsequently. 



[T. R. J.] 



On the History of Insects. By Prof. O. Heer. 



[Leonhard und Broun's Jahrb. f. Miner, u. s. w. 1850, pp. 17-33.] 



The great Class of Insects, which furnishes four-fifths of the ex- 

 isting species of the animal kingdom, has two chief divisions. In • 

 the one (the Ametabola) vre have an imperfect, in the other (the 

 Metabola) a perfect metamorphosis ; that is, in the former there is no • 

 quiescent pupa-state, and the metamorphosis is accompanied by no 

 striking change of form ; in the latter there is an inactiye pupa, • 

 that takes no nourishment, and so great a change of form that only by 

 watching the progress of ih.Q metamorphosis can we recognise the pupa 

 and the imago as being the same animal. The Metabola correspond, 

 as it were, to the flowering plants ; the xlmetabola to the Crypto- = 

 gamia. It is well wortliy of remark, that among Plants the Crypto- - 

 gamic, and among Insects the Ametabolous, first appeared upon our 

 earth. The most ancient forests, composed of tree-ferns, club- 

 mosses, and equiseta, were inhabited by Locustce and BlattcB, the 

 first of insects. There have not as yet been found in the carboni- 

 ferous and triassic rocks any traces of insects that can be with cer- 

 tainty referred to any of the other Insect-orders. And of these 

 Orthoptera at present we know of only six species belonging to these 

 most ancient times, in which indeed insects appear to have been ex- 

 tremely scarce. Nor need we wonder, if we consider that at present 

 also our Lycopodia and Equiseta harbour no insects, and the Fihces 

 very few. The hosts of insects, therefore, that hve on the flowers 

 and their honey, on the fruits and seeds, could not at that time have 

 been in existence, the vegetable world being then destitute of flowers 

 and fruits. 



The ametabolous insects also play the chief part in the Jurassic 

 period. Here they appear as very large Locusts and Dragon-flies, 

 the latter belonging to the MschnidcE * (including the Gomphi) and 

 the Agrionidce, as a few Termites and a long series of beaked insects. 



Near these, however, in the Jurassic rocks occur also some insects 

 of the second division ; namely, a few Flies, an Ant f , and a number 

 of Beetles. The flower-insects, on the other hand (as Bees and 

 Butterflies) j, appear to have been wanting at this period. 



This is also the case in the succeeding period, that of the Chalk, 



* The Libellula Brodiei, Buckman, in Brodie's * History of tlie Fossil Insects 

 in the Secondary "Rocks of England/ is clearly an MscTina. 



t I look upon the Apiaria lapidea, Germar, to be an Ant, on account of the 

 peduncled hind-body. In its bearing also it much more resembles an Ant than 

 a Bee. 



X The Tineites lifhophilus, Germar (Munster, v. 88), is according to my view a 

 Termite. Not only on account of its size can it not be a Moth, but still more on 



