October, 1916.] /k^ 2l7 ''/X 



clistinguisli the various forms that they possess. I AlscTtiiefeeisHgliU ID 

 structviral characters are most difficult to appreciate 



Tlie ? of il.ava seems to be generally divisible im:»v.^TS&OW^^^|^l^ 

 less well-marked varieties, the commouer one with the propodeum 

 geueralh'^ with much less red colour and sometimes without any red 

 markings, and the orbital lines very narrow or often almost interrupted 

 between the cheeks and the line of the anteunal insertions, the other 

 with broader orbital lines and the propodeum with large red markings, 

 either with three red spots on each side, or with two of these imited 

 into one, or with all united. 



The $ of rvfi,cornis that is parasitic on A.fulva makes the closest 

 approach to flava, and might be confused therewith, as it is hardly 

 inferior in size to fairly well-developed specimens of the latter. It 

 always has the propodeum very largely red-marked, the markings on 

 each side often confluent into one large irregular spot, shaped like 

 those of signata. Two examples of this form in Smith's collection are 

 certainly three-quarters of a century old, and, from fading, their 

 resemblance to Jlava is increased, but they remain certainly dis- 

 tinguishable. 



As to the forms of ruficornis that I possess, the hosts of which 

 are species of Andrena other than/wZva, these present great variability, 

 but are not likely to be confused witk jlava. Some of these are 

 extremely like some varieties of N. borealis, or the species called 

 lateralis by Smith (not Saunders). The much longer erect mesonotal 

 pubescence of burealis, and the com/paratively well-developed hairs on 

 the posterior surface of the whole flagelluni of lateralis Sm., are such 

 good and constant characters that others are hardly necessary. Smith 

 himself reinai-ked on the long antennae of his lateralis ; in which 

 respect the species rather resembles flava than ruficornis, although 

 superficially it is entirely unlike any examples of the former. It is 

 quite remarkable for its constancy of pattern and colour in both sexes. 



SYNOPSIS OF (? <? . 



1 (2) Clypeus with only the extreme apical margin pale, the pale line 



sometimes altogether interrupted in the middle ; scape entirely black. 

 (Pubescence of mesosternum pale f viscous with yellow or golden 

 tint ; yellow marking of the cheek not prolonged back along the 

 eye-margins nearly so far as the line of the antemial insertions) 



...horealis. 



2 (1) Scape often pale in front, if black, the clypeus has a conspicuous yellow 



band, which rarely occupies much less than its apical half, or it may 

 be wholly yellow. 



T 



