2 Annals Entomological Society of America [Vol. XI, 



evidence of twelve segments in representatives of the Odonata, 

 and EphemeridcB, and also in Lepisma and other representatives 

 of the Apterygota. 



This subject has since received but little attention. Carriere 

 and Burger (1897) state that the abdomen of embryos of the 

 mason bee is composed of ten segments and a telson (p. 330). 

 Further on it is said that eleven pairs of ganglia are present in 

 the abdomen of embryos (p. 368). The latter statement is 

 probably from the pen of Burger, and clearly indicates the 

 presence of eleven true segments in addition to the telson. This 

 is also seen in the figures. Hirschler (1909) reports finding in 

 Donacia "20 Korpersegmente (eventuell 21, wenn wir aus 

 theoretischen Grunden das 12 Abdominalsegment zurechnen)." 

 His figures — especially figures 62 and 64 — show clearly eleven 

 abdominal segments in addition to the hypothetical telson. 



In the honeybee Biitschli (1870), in one of the earliest 

 accounts of the embryology of this insect, expressly states 

 that there are 17 pairs of ganglia in the ventral chain, and 

 clearly shows three ganglionic swellings in the terminal ganglion 

 in his figure 40. This observation has apparently been over- 

 looked by all subsequent writers on this subject. For example, 

 Grassi (1884), the next investigator after Butschli to study the 

 embryology of the honeybee, states that the ganglionic chain in 

 the trunk consists of only 13 ganglia. 



The writer (1915) reported finding eleven segments bearing 

 neuromeres in the abdomen of embryos of the honeybee and 

 gave figures of the posterior end of embryos showing the devel- 

 opment of this part of the ventral chain. Ten pairs of ganglia 

 and the rudiments of the eleventh pair are formed in the 

 abdomen, the 9th, 10th and rudimentary 11th pairs uniting to 

 form a compound ganghon. The evidence was in this instance 

 rather briefly presented and in fact on review appeared rather 

 unsatisfactory. For this reason it appeared to be desirable to 

 present the evidence in a more complete form and also to add 

 some observations regarding the conditions obtaining in larvae. 



At about the stage designated X by the writer (1915), when 

 the rudiments of the antennae and gnathal appendages are well 

 formed and the development of the organ systems is well under 

 way, sagittal sections, either optical or actual, clearly show that 

 the abdomen is divided into eleven segments, in each of which 

 is a neuromere, representing a pair of ganglia. A few hours 



