BY REV. T. BLACKBURN. 485 



undoubtedly some respects in which I can find no variation, 

 especially the position of the horns, and the shape and sculpture 

 of the retuse area occupying the middle portion of the front of 

 the pronotum. I find very little variation in the females. I 

 may remark that although Sir W. Macleay in his descriptions 

 seems to attach considerable importance to the form of the trans- 

 verse carina at the base of the cephalic horn in the male, that 

 character appears to me quite valueless, being absolutely variable 

 and also varying with the point of view from which it is regarded. 

 There will be seen, w^hen the surface of the head of a Bolbo- 

 ceras is examined, certain arepe marked off by fine raised lines 

 which are arranged in the main on a uniform design in nearly 

 all the Australian Bolbocerata, but which nevertheless vary in 

 some details that appear to be genuinely specific. In males 

 having strongly marked sexual characters on the head, some of 

 the arese are thrown out of form by the horns, etc., and made to 

 assume different shapes, but essentially they are seen to be 

 identical if carefully considered. As it will be necessary in the 

 following pages to refer frequently to these arere and lines, it 

 seems desirable now to enumerate and name them. There is no 

 real dividing line between the clypeus and the remainder of the 

 head; nevertheless it seems convenient to use the word "clypeus." 

 Carrying the eye forward from the front of the pronotum, the 

 first inequality of the surface is an elevation (a transverse carina, 

 often bifid or variously horned, or a mere horn or a tubercle), 

 which I shall call the " frontal elevation." Some distance in 

 front of this is another transverse carina (of very variable shape) 

 which I shall call the " clypeal elevation." The clypeal eleva- 

 tion is returned at its extremities backward (in some species at 

 an angle, in others with a curve) and runs longitudinally in vary- 

 ing length towards the back of the head; I shall call this longi- 

 tudinal carina the " frontal margin," and the area quite or 

 partially enclosed by the frontal elevation, the clypeal elevation 

 and the frontal margins I shall call the "frons." The portion of 

 the head in front of the clypeal elevation (which is divided b}^ 

 fine carinje in most species into the "middle" and the two 



