OF WASHINGTON. 151. 



I shall not now go into the rise of the clypeus and labrum, 

 only to note that in the Chilopod there is a piece bent down 

 between the large and approximate antennas, which, as the an 

 tennae separate, will become more prominent, and as the mouth 

 moves forward will become dorsal in position. 



Regarding the history of the compound thorax theory, it may 

 be well to record that Hagen in 1889 said he thought each seg 

 ment was composed of three, one each for the legs, the spiracles, 

 and the wings ; but his views are not at all in line with mine, 

 and were -unknown to me in 1893 when I broached my theory. 

 In 1900 Mr. Walton, upon studying the coxa, concluded that the 

 thorax was composed of six segments. He was then unaware of 

 the papers by Hagen and myself. Kolbe in his " Einfuhrung " 

 gives practically the same version of the segmentation of the 

 thorax that I have given. Kolbe's work was finished late in 1893, 

 but was issued in parts, and the part dealing with this matter 

 must have appeared about 1891 , although unknown to me in 

 1893. 



Since I have written this paper (which was on the program for 

 presentation last fall) I have seen a paper by Verhoeff (published 

 in May, 1903), in which he accepts the compound nature of the 

 thorax and gives names to the parts, as follows : 

 between head and prothorax Microthorax ; 

 between pro- and mesothorax Stenothoiax ; 

 between meso- and metathorax Cryptothorax. 



He shows that in Japyx the cryptothorax still retains the 

 spiracle, and he finds traces of these segments in various insects. 



BIBLIOGRAPHY. 



Hagen, H. A. Ueber die friiheren Zustande des Libellen, 

 nebst Andeutung tiber Bildung des Thorax. Stett. Ent. Zeit., 

 1889, PP 162-167. 



Kolbe, H. J. Einfuhrung in die Kenntniss der Insekten, 1893, 

 pp. 1 15-1 1 6. 



Banks. N. Notes on the thorax and mouth parts of insects and 

 Chilopods. Am. Nat., April, 1893, pp. 400-401. 



Walton, L. B. The basal segments of the hex-apod leg. Am. Nat., 

 April, 1900, pp. 267-274. 



VerhcefF, K. W. Beitrage zur vergleichenden Morphologic des 

 Thorax der Insekten mit Berucksichtigung der Chilopoden. 

 Nova Acta K. Leop. -Carol. Deutsch. Akacl. Naturfor., 

 LXXXI, No. 2, pp. 63-124. 



