328 Geoffrey Smith 



out to me many peculiar features in the secondary sexual chavacters 

 of the Laraellieornia, many of them concerniug- ([ualitative ditferenees 

 in colour and in strueture which are quite impossible to bring under 

 the quantitative rule under discussion. But a general review of the 

 secoudary sexual characters of the Lamellicornia, in so far as they 

 are quautitatively estimable, atfords the most convincing evidenee 

 of the presence of high and low dimorphism as a differentiating 

 faetor. Frora the mass of material which I have gathered, only a 

 few most striking instances will be selected for discussion here. 

 The two genera Catharshis and Copris belong to the Copridae verae. 

 The males are distinguished from the females by the presence of 

 a projecting thoracic ridge and a salient clypeal hörn, which are 

 rudimentary in the Iemale. In Catharsiiis we may start from C. 

 niolossus (Texttigs. 10 and 11) a large form with a ränge of variability 

 in total length from about 40 — 22 mm., the high males graduating 

 into the low and so into the female condition in their secondary 

 sexual characters. Now as the species of Catharshis get smaller and 

 smaller the sexual ditferenees in the thoracic ridge and the clypeal 

 hörn in the males and females become less and less, until we come 



to exceedingly small forms as 

 C. Mifrons, inenn/s, and opacus, 

 measuring from 15—16 mm. in 

 which there is no external differ- 

 ence in the sexes visible. (8ee 

 Texttigs. 12 and 13 C. laUfwm). 



Fiff. 10. 



l'ij?. J-'. 



Fig. 11. 



In the genus Copris the larger species have highlv marked 

 sexual ditferenees, and here again we pass in a series to Very small 

 f.»rms as C. reflexHs, minutus am\ larriceps, measuring about 11 mm., 

 Ml which the males and females have been entirelv assimilated by 

 tho suppression of the secondary sexual characters. 



In this way the small species of Catharsius and Copris come to 

 converge upon one auother in the most remarkable manuer, but 



