140 THE ANATOMY OF THE HONEY BEE. 



for " tracheal sac," notwithstanding that Sc alone means " subcosta." 

 The symbol T is used for " tergum," and T^, T^, etc., and IT, IIT, 

 etc., indicate individual thoracic and abdominal terga, but TMcl is 

 used to signify " transverse, muscle." And so, in several other cases, 

 it has been found expedient to sacrifice strict uniformity to practical 

 considerations. 



A combination of lower-case letters duplicating one entirely or 

 jDartly of capitals signifies that the part so designated is a part or sub- 

 division of the other. For example, Ten refers to the principal part 

 of the tentorium and ten to a minor part ; PI and pi are subdivisions 

 of the same pleurum ; Lmcl and Imcl are both longitudinal muscles. 



The most logical method of referring symbols to any particular 

 segment of the body would be, perhaps, to prefix them with either a 

 Roman or an Arabic numeral corresponding with the number of the 

 segment. A common objection, however, to both would arise from 

 the fact that entomologists are not at all agreed as to how many seg- 

 ments there are in any region of an insect's body. Furthermore, 

 Roman numerals prefixed to all the symbols necessarily used on a 

 drawing of the thorax, for example, would occupy entirely too much 

 space. Finally, it is very desirable to have a method of referring to 

 repeated structures without implying any segmental connection, and 

 prefixed Arabic numerals are certainly most convenient and sug- 

 gestive for such a purpose. A system often adopted to indicate the 

 segment to which a part belongs, especially in the thorax, .is the use 

 of one, two, or three accents in connection with the abbreviation. 

 But accented symbols lack artistic unity, and some of the accent 

 marks are too easily lost in the engraving and printing. For these 

 several reasons the writer has adopted the following system: 



Numerical order of any repeated structure is indicated by an 

 Arabic numeral placed before the abbreviation, and has no segmental 

 significance. Thus IP, 2P, etc., mean simply " first parapterum," 

 " second parapterum," etc; IG-ng, 2Gng, etc., mean " first ganglion," 

 " second ganglion," etc., without implying that the ganglion belongs 

 to any particular segment. 



Symbols are referred to the prothorax, the mesothorax, or the meta- 

 thorax, respectively, by the figures 1, 2, and 3 placed below and 

 after them, except on the wings, where such numbers designate the 

 branches of the veins according to the Comstock-Needham system. 



The abdominal segments, counting the propodeum as the first, are 

 indicated by the Roman numerals / to X, and, when any one of these 

 is placed before an abbreviation, it refers the symbol to that indi- 

 vidual segment. 



The lower-case letters are used, singly and in pairs, to refer to 

 miscellaneous parts having, in most cases, no individual or general 

 anatomical names. 



