Insect evolution: How did insect wings originate? Elizabeth L. Jockusch, Lisa M. Nagy  Current Biology  Volume 7, Issue 6, Pages R358-R361 (June 1997) DOI: 10.1016/S0960-9822(06)00174-6

Figure 1 A comparison of gene expression patterns in developing Artemia and Drosophila appendages of genes thought to play an important role in patterning. Lighter shading indicates lower levels of gene expression. In the Artemia limb, proximal is to the left and dorsal at the top; engrailed expression is stippled in Artemia to show that it occurs only in the posterior portion of the limb. The Drosophila leg disc is oriented with proximal to the left and anterior at the top. The dashed outlines of rings of pdm expression in the Drosophila leg indicate that they exact positions are not known. (Based on data in [4,6–8,11].) Current Biology 1997 7, R358-R361DOI: (10.1016/S0960-9822(06)00174-6)