— 2o6 — 



eleven-jointed antenna.-, is, despite the difference in the form of these an- , 

 tenniv most closely allied to them. Now as the Geotiypini are laparosticii I 

 Lamellicornes I consider myself justified in placing this genus which also 

 has but eleven antenna! joints in this division. That this placing was 

 due only to reasoning by analogy, e.xtraordinary as it may seem, is forceil 

 upon one by the fact that he nowhere speaks of having examined the ab- 

 domen for the position of the stigmata, and positively mentions that the 

 specimen first described by him hail hail the abdomen destroyed. 



But what, actually, is the structure of this abdomen } Undoubtedly, 

 in view of the many characters contradicting the relationship with the 

 Geotrypini, an answer to this question was of primary importance, because, 

 pro- or con. decisive. I, therefore, with the growing conviction that Pleo- 

 coma had nothing in common with \\\t Geotrypini, but despite the eleven- 

 jointed antennae, could belong only to the Melolonthini, did not hesitate 

 a moment about obtaining certainty by an e.xaminaiion of the carefully 

 removed abdomen of one of my specimens. This examination proved 

 positively, what I fully expected, that the large spiracles of the second and 

 third, and the smaller ones belonging to the fourth and fifth abdominal 

 segments, had, in Pleocoma, precisely the same siluaiion as in Melolontha, 

 i. e, on the superior portion of the ventral segments, and not on the 

 membrane connecting the corneous dorsal and ventral plates as in Geo- 

 trypcs and Copris. 



From this it appears at once that P/eacoma does not belong to the 

 ScarabLcidw laparosticii aX. all, and that the relationship assumed by Leconte 

 to exist between this genus antl the Geotry/ini and Copr/ni -as at first stated, 

 or the Geotrypini and Trogini, as finally stated, was entirely without base. 

 Certainly he would have been much nearer right in the conviction at first 

 forced upon him, of its relation to the Dynastnii •&% agreeing with them, 

 this insect is at least a p/turostict. But that, even disregarding the entirely 

 different situation of the spiracles, Pleocoma shows no real relationship to 

 the Geotrypini hwi only a certain habitual agreement with some of them, 

 and an agreement in unimportant details with others is fully demonstrated 

 by an examination of all really important characters. 



As to the habitus of Pleocoma, it is not to be denied that it reminds 

 one of the females Ceratophytis, Fish. ; but of all the Geotrypid forms it 

 reminds one of that only. As Leconte himself .says a closer comparison 

 is at once opposed by the entirely different sculpture of the elytra, and 

 in this respect the resemblance to Syrichthus wovdd he vastly more ob- 

 vious. Further, as regards the agreement of the prosternuni with that 

 oi Athyreus prominently mentioned by Leconte, 1 am utterly unable to 

 discover any such ; in Athyreus it forms an inflated trigonate or heart 

 shaped jjlate, and at this j)oii)t in Pleocoma there is only a small. 



