BY REV. T. BLACKBURN. 487 



In Westwood's work on the Bolbocerata much importance was 

 attributed to the form of the apical portion of the right mandible; 

 but in the following pages I have not relied upon it, chiefly 

 because there areman}'' specimens in which it cannot be definitely- 

 ascertained without detaching the mandible. The external out- 

 line of the left mandible, however, is variable specifically and is 

 easily examined; I have therefore treated it as of practical value 

 in determining species. 



The pronotum of all the Australian Bolbocerata known to me 

 bears a large, usually ill-defined impression on either side some- 

 what behind the middle and near the lateral margin. I have 

 called this by the name " sublateral fovea." It is variable in 

 form both as an individual and specific character, and does not 

 seem to me easy to use for distinguishing species. 



The front margin of the pronotum usually bears a more or less 

 distinct small impression on either side of its middle. In the 

 species of the First Group (only) this impression takes the form 

 of a very deep sharply defined circular fovea or " hole." Beyond 

 that, I have not found it useful as a distinctive character. 



I must not conclude these preliminary remarks without referring 

 to the extremely valuable assistance I have received from Mr. 

 W. W. Froggatt, who with most obliging courtesy has examined 

 those of the species described by Sir W. Macleay that were 

 unknown to me and drawn sketches of those parts on whose 

 structure the following tabulation is based. Important parts of 

 this memoir, therefore, are due to his, rather than to m)% research. 



Tabulatiox of Groups of Bolboceras. 



Group i. — Upper face of hind tibise multicarinate transversely. Front 

 margin of pronotum with two very deeply impressed small round foveae. 



Group ii. — Upper face of hind tibi® with only one transverse carina above 

 the cariniform apex. Front margin of pronotum not having deeply 

 impressed foveae. Carinas dividing the clypeal areae do not meet in the 

 middle of the clypeal elevation. 



Group iii. — Upper face of hind tibise and front margin of pronotum as in 

 Group ii. Carinae dividing the clypeal areee meet in middle of clypeal 

 elevation. 



