484 Mr. Gilbert J. Arrow 071 Characters and Relationships 



is known. It is remarkable that, while the Laparostict 

 condition must certainly be regarded as more primitive 

 than the Pleurostict, all the least primitive forais of the 

 antenna are found in the Laparostict division, and one of 

 the most highly modified types of all {Lethrus) occurs 

 in the family in which alone (except in Pleocoma) the 

 primitive number of eleven joints still exists. 



It is interesting to find the habits of Pleocoma. prac- 

 tically identical with those of Pachyims, the females of 

 both being wingless and remaining always below the 

 surface of the ground, where they are sought out by 

 bevies of males. Clitopa and other Melolonthinc genera 

 have similar habits, but there is no resemblance whatever 

 to those of the Geotrivpinac. 



In view of all the facts it seems to me that both 

 Pleocoma and Pachypus, although by no means closely 

 related, are probably more nearly related to each other 

 than to any other known forms, and that, while they are 

 best classed among the La/parosticti, they are scarcely less 

 related to the Pleurostieti. 



Prof. Kolbe has added to the Lamellicorn series the 

 family Si/nffliidar, consisting of the small genus Si/ntelia, 

 which he regards as forming a link with the Staphylinid 

 series through the Histeridac. But the latter family is 

 probably one of the latest branches of that series and 

 Syntclia is in many respects by no means primitive. The 

 antennae are of a well-developed Clavicorn type, and if 

 there is any special relationship between the two great 

 series, which is as yet very hypothetical, I think the 

 Synteliidac are more naturally placed on the Staphylinid 

 side. If I am right, however, in regarding the genera I 

 have just discussed (those with many-lamellated antennae) 

 as the most primitive Lamellicornia, then the ancestry of 

 the series should probably be traced in quite another 

 direction. I may point out, as of some significance, that 

 the Lamellicornia are invariably characterized by having 

 only a single articulated spine to the front tibia. In the 

 Synteliidac, Histeridac, Silphidae, etc., there are two. 



The following Table indicates what appear to me to be 

 the primary subdivisions of the Laparostict Scarabacidae — 



Antennal chib of more than 3 joints. 



Antennae 11 -jointed Pleocominae. 



Antennae 8-jointed Pachypodinae. 



