37 



An Insect Wing of extreme Simplicity from the Coal- 

 formation. 



At the last general meeting of the Society, the wing of a fossil 

 cockroach from Pennsylvania was exhibited; in consequence of 

 which Dr, Packard sent me a fragment of anthracite shale preserved 

 in the Museum of the Peabody Academy of Science at Salem, bear- 

 ing certain impressions. The specimen was taken from a coal hod in 

 New York City by Mr. James Angus of West Farms, and is sup- 

 posed to have originated from Pennsylvania. 



Upon this piece of carbonaceous shale is the well defined wing of 

 an insect of marked simplicity. It is small, and very broad in pro- 

 portion to its length, with a costal margin very much arched apically, 

 a pointed subfalcate tip and an anal region broadly lobed. The 

 number of principal veins is six, arranged to a certain extent by 

 pairs, since each pair approximates to a greater or less extent at the 

 extreme base. I have long maintained that the normal number o* 

 veins in the wings of insects is six (as upheld by Heer and others), 

 and that they were arranged by pairs; but that in many insects one 

 or another, or indeed most of the veins, might become aborted, and 

 that they become ditFerentiated in the various groups in different 

 ways, sometimes one and sometimes- others playing the principal role 

 and one or more, although not always the same, being quite simple, 

 while others by branching support the principal part of the frame- 

 work of the wing. In this ancient wing, however, scarcely the slight- 

 est differentiation has begun, each of the veins branching near the 

 base, again with slight diversities before the middle of the wing, and 

 again either (in the upper half) at, or (in the lower half) beyond the 

 middle of the wing; there are also occasional additional branches; 

 but each principal vein appears to branch to an almost exactly equal 

 extent ; the region covered by the ujipermost pair of principal veins 

 and their branches, however, exceed that covered by either of the 

 other pairs; it is indeed about ecjual to the other two combined, 

 which share equall}' between them the lower half of the wing. The 

 o-eneral resemblance of the whole to the distribution of the tracheae 

 in the forming wing of a caterpillar is very striking; and if the the- 

 ory of the wing that I have maintained be correct, this is precisely 

 the number and mode of distribution of the veins which one would 

 predicate for the primeval wing. Hitherto we have arrived at noth- 

 ing of the sort; in all the wings we have yet seen from tiie Carbon- 



