283 
persistent, though not shown on segment 2, and not as distinct on 
segments 3 to 5 as before; but on segments g and ro they seem to 
stand out distinctly from the surface of the segment, though the 
author did not letter them. In Fig. 28, representing a still more 
advanced step, there are no traces of these deciduous structures, but 
the normal abdominal legs (on segments 3-6 and 11) are distinctly 
drawn and lettered. 
Though with some hesitation I yet regarded the figures as repre- 
senting these deciduous structures, but was unable to read the Rus- 
sian text. 
In his valuable treatise, Ueber die Polypodie bet Insekten- 
embryonen (1888), Graber describes and figures the embryo of 
Gastropacha quercifolia, stating that there were no traces of these 
temporary structures to be seen. He also states that no temporary 
abdominal legs were found either by Buetschli, or by Grassi, in 
the honey bee. None have been observed in the Diptera by 
Weismann and others. Hence it appears, up to this date, that they 
only occur in the orders below those named above. Graber throws 
some doubt on Kowalevsky’s observations, and states that Ticho- 
miroff also did not discover them. On this account he is led to 
consider the abdominal appendages of caterpillars as secondary 
structures. | 
In his interesting article, ‘‘ On the Appendages of the First Ab- 
dominal Segment of Embryo Insects,’’ Mr. W. W. Wheeler * dis- 
cusses this question, and gives a list of the species and orders of 
insects in which these deciduous abdominal appendages have been 
found. His list shows that in all the Orthoptera which have been 
studied, pleuropodia, viz., the temporary appendages of the first 
abdominal segment, and in general those of the succeeding seg- 
ments, have been observed in the embryos of all the Orthoptera yet 
examined. In the Hemiptera they have not been observed in three 
species of Aphis, but have been detected in Cicada and Zaitha. In 
the Coleoptera they apparently may or may not be present, for ex- 
ample, they have been seen in Hydrophilus, Acilius, Melolontha and 
Meloé, but not in the chrysomelid genera Lina and Doryphora. The 
neuropterous genus Sialis and the trichopterous genus Neophylax 
possess them. He also states that pleuropodia do not occur in the 
honey-bee embryo studied by Buetschli and by Grassi. 
* Trans. Wisconsin Acad. Sciences, etc., viii, September 20, 1890. 
