34 ILLINOIS BIOLOGICAL MONOGRAPHS [352 



may be found flush with the body surface, when they are spoken of as being 

 sessile. The glandubae are especially conspicuous in the larvae of the 

 Diprioninae and Pachynematus. The slime-glands of Caliroa have semi- 

 sessile glandubae which are few in number. The glandubae are constant 

 in their type, presence, general arrangement, and location, within genera 

 and subfamilies. 



Formulae of Segmented Appendages. — For convenience in designating 

 the size and relationship of various segmented appendages, the resort 

 has been made to various so-called formulae. The segments of an appen- 

 dage are numbered, beginning with the proximal segment. In a formula 

 numbers of the segments are arranged in the descending order of magni- 

 tude, and those of equal dimensions are placed in a parenthesis. For 

 example, the expression "antennal formula: (2,5), 3, 4, 1" shows that the 

 antenna is composed of five segments and that segments 2 and 5 are equal 

 in length but longer than the others, and that segment 4 is shorter than 

 segment 3 but longer than the first or proximal segment. 



