Hymenoptera aculeata collected in Alfjcria, 209 



Andrena minutula, group of. 



This exceedingly diflScult section of the genus requires 

 a complete revision, and as I have neither the material 

 nor opportunity to prepare one I am obliged simply to 

 indicate the number of forms contained in the collections 

 and where possible to assign them to described species, 

 where that is impossible I give the characters which I 

 notice as belonging to each, I think when I explain the 

 position in which this section now stands I shall not be 

 accused of undue cowardice in hesitating to refer the more 

 obscure species to any of the descriptions now extant. I 

 have spent months over this group and feel sure that no 

 satisfactory result can be obtained without having the 

 type specimens of all the species under one's eye and 

 providing a complete synopsis of them. 



There are over 80 presumed species described, of which 

 nearly half are known by one sex only (the ^ ), in those 

 where the $ is described I can find no allusion to the 

 forms of the apical segments and armature. These give 

 very reliable though in some cases slender characters, 

 and without the help of these I have been unable 

 even from the descriptions of celebrated Hymenopte- 

 rists to determine my species. The sculpture of the 

 clypeus and abdomen appears to me to be more or 

 less variable although there seem to be definite types 

 of sculpture which keep distinct notwithstanding the 

 variations in each. Another difficulty arises as to the 

 essential characters of the males. To examine these, 

 unless they have been extracted when fresh, means to 

 destroy more or less the specimen and to make a proper 

 description of its external chaiacters impossible. Mr. 

 Morice, who collected a large number of males at Algiers, 

 first pointed out to me several forms of armature amongst 

 his captures and in dissecting my own taken by Mr, Eaton 

 I find others. Of all these I propose to give diagrams as 

 I think no description will satisfactorily point out the 

 distinguishing characters. I had hoped that the relative 

 proportions of joints 1, 2 and 3 of the flagellum might 

 have afforded reliable characters, but they are so nearly 

 the same in most of the species and appear to vary so in 

 accordance with the position from which they are regarded 

 that very little satisfactory evidence can be got from 

 them, 



TRANS. ENT. SOC, LOND. 1908. — PART II. (.SEPT.) 14 



