THE SEGMENTATION OF THE ABDOMEN OF THE 

 ==::. HONEYBEE (Apis mellifica L.). 



Jas. a. Nelso n, Ph. D., 

 Bureau of Entomology7 Washington, D. C. 



The determination of the number of segments represented 

 in the insect body has proved sufficiently interesting to attract 

 the attention of a considerable number of morphologists. In 

 this field the segmentation of the head has been the more 

 perplexing part of the problem as well as the more difficult, in 

 contrast with the segmentation of the trunk. The latter, how- 

 ever, has the advantage of being capable of a reasonably certain 

 solution. The earlier workers in this field regarded the trunk 

 of the insect as consisting of ten, or in some cases, of eleven 

 segments. The tenth or eleventh segment, recognized as in 

 •jmost respects comparable to those anterior to it, was regarded 

 as constituting the terminal or end segment, bearing the anal 

 opening. For instance, in Hylotoma the eleventh segment bears 

 appendages and possesses a neuromere (Graber 1890) and in 

 Xiphidium this segment also bears a pair of appendages, the 

 cerci (.Wheeler 1893). Heymons (1895, 1895a), paid especial 

 attention to this problem and introduced the conception, now 

 generally accepted, of a terminal segment or telson — stated to 

 be especially evident in Gryllotalpa — comparable to the telson 

 of the Crustacea, containing the anus but differing from the 

 other segments in not having paired appendages or other 

 strictly metameric organs. In addition to the appendages of 

 the eleventh segment Heymons found in Phyllodromia well 

 defined coelomic sacs in this segment. In later papers (1896, 

 1897), Heymons has elaborated this conception, finding plain 



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