52 



such low insects as have hitherto been found in carbonifei'ous forma- 

 tions, the anal or posterior vein (which lies on the inner side when 

 the wing is at rest) is always niultivenose, and often occupies with 

 its veinlets a large share of the wing, so here the innermost principal 

 line is most numerously branched, and with its branches covers 

 nearly a third of the segment. At first glance, however, these 

 branches, which run transversely across the segment, appear to be 

 continuous with those springing from the innermost line of the oppo- 

 site side, which would be quite inconceivable in the wings of an 

 insect; a close examination, however, shows that there is but a sin- 

 gle one of these branches which actually traverses the segment; the 

 others nearly meet, but interdigitate, and the break in the one might 

 be judged to be invisible through the imperfection of preservation; 

 so that the I'esemblance to an insect's wing is even more striking, 

 and this circumstance long led me to maintain the possible insectean 

 nature of the fossil. All the other lines, moreover, could be referred, 

 without violence, to one or another of the principal veins of a wing, 

 with the exception of those next the margin, whose origin could be 

 supposed to be lost on the side of the fossil. Another feature ren- 

 dered tliis theory more tenable; a microscopic comparison of the 

 surfaces of the antepenultimate and penultimate segments of the 

 abdomen showed a difference in texture, the former being marked by 

 a very obscure and minute reticulation, which could not be seen on 

 the latter; this difference was improbable, or at least unexpected, in 

 two contiguous segments of a crustacean abdomen, but on the the- 

 ory that the lines rejjresented the veins of an insect's wing, seemed 

 to indicate that the hind wing was membranous, and the fore wing 

 more or less coinaceous in texture, as in Orthoptera. On the wing- 

 hypothesis, however, the insect must have been extraordinary in 

 character, even apart from the gigantic appendages of the abdomen. 

 For, judging by the direction of the supposed veins, the front Avings 

 would then have covered only the segment which bore them, and 

 would not have protected the hind wings ; while the latter would 

 have reached the tip of the abdomen with no plication of the anal 

 area. The abdomen, also, notwithstanding it bore so enormous a 

 pair of appendages, would have been shorter than the thorax, which 

 in a comparatively slender insect would be altogether anomalous. 



All doubts, however, concerning the real nature of the fossil were 

 put to rest on the reception of some Devonian specimens of Ditby- 

 rocaris kindly lent me by Professor James Hall, and Avhich he will 



