234 '^^^^ Irish Naturalist. September, 



(Ormerod, '68 ; Pack-Beresford, '02) to the fact that the nest 

 of V' rufa revSembles in texture and construction the nests of 

 the tree-wasps more closeh^ than those of the other ground- 

 building species ( V. vtdgaris and V- germanica') ; and that its 

 nest, usuall}^ not buried deepl}^ rests attached to the roots of 

 grasses, in a cup-shaped hollow. It may be concluded from 

 this that V' rufa has adopted the habit of building ground- 

 nests rather recent!}-, though it is of interest to note that, at 

 least sometimes, it builds a truly underground nest (Janet, '03). 

 Then we find that ]\ sylvestris, which habitually builds in 

 treeS; occasionally makes a ground-nest (Smith, '58) ; here 

 apparentl}" we see the beginning of the change in habit which 

 has alread}' been carried far b}^ the rttfa-aiistriaca race. In 

 most of the points wherein V- a2istriaca differs from V. rufa 

 it approaches the tree-wasps ie.g', the hair>^ shins, the 3'ellow- 

 streaked scape) ; and we see in this further evidence that 

 austriaca is to be regarded as the older form. Moreover, as 

 all the workers of these wasps are clearh' referable to V. rufa^ 

 it seems that V- austriaca points us back to a time in the 

 history of the race before the worker had become differentiated 

 from the queen. The workers doubtfull)' referred by Smith 

 to his r^. arborea (43, p. 171 ; Ormerod '68, pi. 3) might well be 

 considered varieties of V- rufa in which the reddish abdominal 

 markings are wanting, while a 3-ellow streak on the scape of 

 the feeler and additional yellow marks on the scutellum are 

 present. Unfortunatel}- he gives no structural details of 

 these workers. Marchal ('96) has shown that, even among 

 our commonest social wasps, a sharp distinguishing line 

 between the two forms of female — the queen and the worker — 

 cannot alwa^-s be drawn. 



Some ver}^ interesting problems as to the origin of specific 

 distinctions maj^, perhaps, be elucidated b}- the relationship 

 between our two wasps. Their structural differences are quite 

 sufficient to warrant " specific " distinction in the ordinary 

 sense of the term, so that if our view be established, the de- 

 velopment of rufa offspring from austriaca parents would 

 be a v^ery striking instance of "discontinuous variation" 

 (Bateson, '94). It would, indeed, furnish an instance in sup- 

 port of Bateson's theory '' that the Discontinuity of Species 



