INTRODUCTION. 13 



eiarhtli occasionally protrudes beyond the apex of tlie 

 sixth, as in the $ of Pompilw:, Andrena, &c., where 

 althougli the seventh is hidden, the eighth forms the 

 visible apical segment. The posterior opening as a rule 

 is apical, but in some genera such as Megachi/e Osiiiia, 

 &c., it is inferior, and in these cases several of the ventral 

 segments of the abdomen are " telescoped " up as it were, 

 and hidden under the preceding segments. The eighth 

 segment in most of the genera is hidden, but it can nearly 

 always be dissected out ; it generally clings closely to the 

 genital armature in the (J, and some authors have more or 

 less confounded it therewith. In some genera the eighth dor- 

 sal segment in the c? bears two small palpiform organs, 

 called penici li. The terminal segments and the genital 

 armature in the (J afiford most valuable characters. The 

 latter organ consists of two pairs of forceps, the outer ones 

 or sfipit&i springing from a basal ring called the eardo ; the 

 inner ones are called the sacjlttse, and lie between the 

 stipites. Over these at the base lies the s^yafha, and between 

 these can be exserted the intromittent organ. These two 

 pairs of appendages probably denote the existence of a 

 tenth and eleventh abdominal segment, and probably the 

 eardo and spat/ia are vestiges of the original somites ; the 

 apical portion of the .itij.ies is often dilated and modified in 

 the Anthophila, and has received the name of the lacinla. 

 In the genus Apis the S armature is quite diflerent to that 

 of any other genus, the stipites being wide and triangular, 

 and the sagittw, probably being internal and represented by 

 what is called the " bean," i.e. the plates which protect 

 the spemiatophore. I can see nothing in any other genus 

 to correspond to the pneitnoj)hijses of Apis. For further 

 remarks on the terminal male segments of the Aculeata I 

 may refer to the " Transactions of the Entomological 

 Society," 188 t, p. 251 et srqq., where I have gone into the 

 subject at greater length than I am able to do here. 



In the ? the abdominal segments are nearly always 

 simple, except the dorsal valve of the sixth, which is often 



