340 MEMOIRS ON THE COLEOPTERA 



Tribe CREMASTOCHEILINI. 



The moderately numerous genera of this important section of the 

 Cetoniinae have a peculiar facies distinguishing them from either 

 the preceding Cetoniini or the Trichiini, which follow, and their 

 more specialized structural features, such as the cupuliform mentum, 

 tetrahedral basal joint of the antennae, serving to close the clypeo- 

 frontal gap at the sides, and prominent tubuliform posterior spiracles 

 of a large proportion of the species, as well as the inquiline habits 

 of many others, also separate them widely from any of the neigh- 

 boring groups, so that the proposal of full tribal rank for them seems 

 amply justified. Sexual differences, at best not very marked in 

 most of the Cetoniids, become virtually altogether unobservable 

 here, so that the sexes will not be referred to separately. In a long 

 series of Cremastocheilus schaumi Lee., at hand, I find that the men- 

 tum is flat, with abruptly reflexed margins in some specimens, and 

 deeply, subevenly concave in others; this does not occur, at least in 

 so marked a way, in any other species of Cremastocheilus before me, 

 but is observable to exactly the same extent in the genus Trinodia, 

 where it appeared to form a remarkable specific character, until 

 accidentally noticed in the very homogeneous schaumi series 

 mentioned ; it is probably a sexual character. 



Africa and North America are now, singularly enough, the prin- 

 cipal abodes of these peculiar insects, the former doubtless being 

 their place of origin, though some of the largest species of the tribe, 

 such as Cyclidius elongatus, inhabit South America, whence the 

 North American archetypes were derived through migration in 

 geologic time probably not so very long ago. The rupture of the 

 South American African land connection was much more remote 

 in time, as shown by the complete lack of harmony prevailing 

 between the members of the tribe now inhabiting these two conti- 

 nents. The tribe is also represented in the East Indies and China, 

 through migration from Africa by way of the Madagascar Ceylon 

 bridge, but it is wholly unknown in Australia apparently. 



The North American species are assignable to five distinct genera 

 as follows: 



Pronotum not trilobed 2 



Pronotum trilobed longitudinally; basal thoracic angles prominent. . . .5 

 2 Basal angles of the prothorax not at all prominent 3 



