676 



SCIENCE. 



[N. S. Vol. IV. No. 97. 



would occupy a great deal too much of your 

 time. An immense number of species are 

 found in the Palaeozoic rocks, and these are 

 considered by Scudder, the great authority 

 on fossil insects, to form an Order, the 

 Palseodictyoptera, distinct from any of the 

 existing Orders. The latter, he believes, 

 were evolved from the former in Mesozoic 

 times. These views do not appear to derive 

 support from the wonderful discoveries of 

 M. Brongniart* in the Upper Carboniferous 

 of Commentry in the Department of Allier, 

 in central France. Concerning this mar- 

 vellous assemblage of species, arranged by 

 their discoverer in 46 genera and 101 

 species, Scudder truly says : 



'' Our knowledge of Palaeozoic insects will 

 have been increased three or fourfold at a 

 single stroke * * * ]S"o former contribution 

 in this field can in any way compare with 

 it, nor even all former contributions taken 

 together." f 



When we remember that the group of 

 fossil insects, of which so much can be 

 aflBrmed by so great an authority as Scud- 

 der, lived at one time and in a single local- 

 ity, we cannot escape the conclusion that 

 the insect fauna of the habitable earth dur- 

 ing the whole Palseozic period was of im- 

 mense importance and variety. Our knowl- 

 edge of this single group of species is 

 largely due to the accident that coal-mining 

 in Commentry is carried on in the open air. 



Now, these abundant remains of insects, 

 so far from upholding the view that the ex- 

 isting orders had not been developed in 

 Palseozic times, are all arranged by Brong- 

 niart in four out of the nine Orders into 

 which insects are usually divided, viz: the 

 Orthoptera, Neuroptera, Thysanoptera and 



*Charles Brongniart. — ' Recherches pour servir a 

 I'Histoire des Insectes fossiles des temps primaires, 

 pr^c^d^es d'une Etude sur la nervation des ailes des 

 Insectes.' 1894. 



tS. H. Scudder, Am. Journ. Sci. Vol. XLVII., Feb- 

 ruary, 1894. Art. \'iii. 



Homoptera. The importance of the dis- 

 covery is well seen in the ISTeuroptera, the 

 whole known Palaeozoic fauna of this order 

 being divided into 45 genera and 99 species, 

 of which 33 and 72 respectively have been 

 found at Commentry. 



Although the Carboniferous insects of 

 Commentry are placed in new families, 

 some of them come wonderfully near those 

 into which existing insects are classified, 

 and obviously form the precursors of these. 

 This is true of the Blattidse, Phasmidae, 

 Acridiidae and Locustidae among the 

 Orthoptera, the Perlidae among the Neu- 

 roptera, and the Fulgoridae among the 

 Homoptera. The differences which sepa- 

 rate these existing families from their Car- 

 boniferous ancestors are most interesting 

 and instructive. Thus the Carboniferous 

 cockroaches possessed ovipositors and prob- 

 ably laid their eggs one at a time, while 

 ours are either viviparous or lay their eggs 

 in a capsule. The Protophasmidae resemble 

 living species in the form of the head, 

 antennae, legs and body ; but while our 

 species are either wingless or, with excep- 

 tion of the female Phyllidae, have the an- 

 terior pair reduced to tegmina, useless for 

 flight, those of Palaeozoic times possessed 

 four well-developed wings. The forms 

 representing locusts and grasshoppers 

 (Palaeacridiidae) possessed long slender an- 

 tennae like the green grasshoppers (Locus- 

 tidae), from which the Acridiidae are now 

 distinguished by their short antennae. The 

 divergence and specialization which is thus 

 shown is amazingly small in amount. In 

 the vast period between the Upper Carbon- 

 iferous rocks and the present day the cock- 

 roaches have gained a rather different wing 

 venation, and have succeeded in laying 

 their eggs in a manner rather more special- 

 ized than that of insects in general ; the 

 stick insects and leaf insects have lost or 

 reduced their wings, the grasshoppers have 

 shortened their antennae. These, however, 



