LI^^yEAX SOCIETY OF LOXDOy. 49 



memoir and also because I have recently had the opportunity of 

 studying the details of the mimetic likeness *. The antenna) 

 of the Fossorial Wasps, the models, are of moderate length (about 

 one third that of their mimics), rather stout with a peculiarly 

 emphasised annulation, in colour usually black with a yellow tip. 

 The antenufe of the Locustidce are very long, of almost hair-like 

 fineness, the annulation inconspicuous, tlie colour uniformly dark 

 with no change at the tip. The antenna of Scaphura possesses all 

 the Locastid chai'acteristics for the distal two thirds of its length. 

 The basal third, however, is thickened to the diameter of the 

 Fossor's antenna: it has a strongly pronounced annulation and 

 its terminal segments are yellow. At a little distance the hair- 

 like two thirds are invisible and all that is seen is tlie thick 

 yellow-tipped part resembling the entire organ of the model. 

 To these mimetic details must be added a blue-black iridescence 

 of the abdomen, and above all the great modification which has 

 taken place in the movements, involving changes in the nervous 

 and muscular systems ; for the Locustid resembles its Fossorial 

 model and departs from its own group in " tlie very curious habit 

 of flying and running alternately and of running short distances 

 with expanded wings "f. 



It is unreasonable to suppose that such a resemblance as this 

 can have been evolved except by successive stages and in the 

 course of a long period of time. 



I. Conclusion. 



It may be considered tiiat it was unnecessary to devote my last 

 Presidential address to the attempt to prove ttiat sniall variations 

 are inherited and that mimicry once started has been evolved by 

 tlie accumulation of small hereditary variations. I have done so 

 because the subjects happen to be those at which I have worked 

 for many years, but also because the views I have attempted to 

 controvert are typical of a restless spirit which, without any real 

 knowledge or serious investigation, seeks to overturn and to 

 destroy. Destructive criticism based on research is a very dif- 

 ferent thing from an offhand attempt to call in question. 



To throw doubt on the germinal origin and hereditary nature 

 of the differences which distinguish geographical races, and thus 

 on the reality of the races themselves, is merely a manifest- 

 ation of that gratuitous and unnecessary disturbance which, 

 especially in this country, has accompanied much interesting 

 and excellent work at the present day. Although sufficiently 

 disconcerting to those students of geographical biology who take 

 these hasty and unfounded conclusions too seriously, it is how- 

 ever but a slight effort of the " spirit that denies ", as compared 



* Proc. Ent. Soc. Loud., 19f3, pp. 1-liii. 



t On the evidence of Dr. Adalbert Seitz, who has often seen model and 

 mimic flying in tbe same locality near Santos, Brazil. Froc. Ent. Soc. Lond., 

 I'.IKi, p. li. 



LINX. SOC. PROCEEUIXGS. — SESSION 1915-1916. e 



