68 REPORT—1845,. 
On the results of recent Researches into the Fossil Insects of the Secondary 
Formations of Britain. By H. E, Srricxtanp, M.d., F.G.S. 
Fossil insects were, till recently, very little known in the secondary rocks of Britain, 
and the only examples were those from the Stonesfield slate, one from the lias, and 
a few from the coal measures. The very large additions to our knowledge of fossil 
entomology, made by the Rev. P. B. Brodie, have been derived from two principal 
grant, the Wealden and the lias. In the Wealden no less than seventy-four insect 
orms have been described and figured by Mr. Westwood from Mr. Brodie’s speci- 
mens. These are generally remarkable for their small size, from which, and frum 
their zoological characters, Mr. Westwcod infers that they belong to a temperate 
climate. The gigantic beetles, locusts and Cicade of our modern tropics are here 
wanting, and the specimens consist, with very few exceptions, of small Curculionidae, 
Tipule, Libellule and Aphides, such as swarm at this moment in European climates. 
This then is a very remarkable fact, when taken in connection with the gigantic 
reptiles and remarkable forms of vegetable life which occur in the Wealden forma- 
tion, and which by analogy we must refer to a tropical climate. We must either 
suppose, what is scarcely conceivable, that insects of European forms could co-exist 
with tree-ferns and other tropical productions, or what is perhaps more probable, 
that the insects ofa cooler climate floated down some vast river into the great Wealden 
zestuary, just as the insects of Upper Canada or the Rocky Mountains might be car- 
ried by the Mississippi, in the present day, into juxtaposition with the alligators and 
palm-trees of the Gulf of Mexico. A similar anomaly is presented by the insects, 
first discovered by Mr. Brodie, and afterwards collected by Mr. Hope, the author, and 
others, in the lower lias of Gloucestershire and the adjacent counties, Of many 
hundred specimens examined by Mr. Westwood, the whole present indications of a 
temperate climate, a conclusion wholly opposed to that which we are accustomed 
to draw from the vertebrate and molluscous fauna of the same epoch. We must 
here, as in the case of the Wealden insects, reconcile this apparent discrepancy by 
supposing that the insects were drifted from cooler climates to the spots where we 
now find them. There are probably no organic bodies of such delicate structures 
which are capable of floating to so great distances as insects ; their extreme lightness, 
and the strong materials of which their corneous parts consist, would enable them to 
float down rivers and to be diffused far and wide over the sea, there to be imbedded 
with truly marine products. In conformity with this view, we find that the insects 
of the Wealden, and still more co of the lias, consist chiefly of Coleoptera and other 
strongly compacted forms, that they most commonly present only detached portions 
of the entire insect, and such portions (chiefly wings and wing-cases) as are the most 
compact and durable. There is therefore no doubt that these insect remains have 
been drifted from the land into the sea, in other words, from higher ground to lower; 
and we have only to suppose that the original habitat of these insects was sufficiently 
elevated to supply them with a cool or temperate climate, and the whole difficulty 
is removed. 
Another very unexpected result of the examination, by a skilful entomolcgist, of 
these fossil insects, is the remarkable affinity which they present to existing forms ; 
even in so ancient a deposit as the lias, we find no insects of decidedly new types of 
organization ; they are in almost every instance referrible to families, and frequently 
to geneta, which belong to the existing fauna. In one instance only has Mr. West- 
wood vetitured to propose a new generic name, and it is remarkable that the pecu- 
liar form so indicated is common both to the Wealden and the lias. It would aps 
peat, therefore, that from the time of the lias to the present day, the class Insecta 
has undergone a far less amount of alteration, either by the extinction of old forms 
or the introduction of new, than any other large group of the animal or vegetable 
kingdom with which we are acquainted. It was indeed well known that the different 
classes of the animal kingdom vary greatly in what we may call their amount of 
durability ; that the higher groups of vertebrata, for instance, present a rapid suc- 
cession of forms as we descend the chronological scale, while certain mollusccus and 
infusorial structures are continued with little or no change during vast geological 
periods; but perhaps there is no other instance of so remarkable a persistency of 
character in a whole class of animals, as that which is presented to us in comparing 
the insects of the lias and Wealden with those of the existing fauna, 
