— 208— 



the stem or fiinicle. Even lliose undeniable hal)itiial analogies which the 

 genus lias with the Dynastini in color, sculpture of elytra, prolongation 

 of front, horned head, indented thorax, &c. , cannot obtain against this 

 decisive character ; thougli it was these very points, which are not usual 

 in the Melolonlhidw, which prevented the recognition of the genus as a 

 member of that group and led to its association with entirely heterogenous 

 forms. 



In fact Plcocoma does not only not lack any of the characteristics of 

 a Meloloiithid antennae, but even possesses all the peculiarities in the most 

 prominent form. To be sure, against this, the number of jcjints, eleven, 

 might be urged, as all hitherto known genera possess only 8-, 9-, or 10- 

 jointed antenniv. But in view of the already known variability in number 

 of antennal joints the fuiiher increase by one could be the less surprising, 

 as eleven is evidently the original and normal number, and the decrease 

 to 10, 9 and 8 can be considered only an departure from the normal 

 structure, aliliough it is one which among the Lamellicorns is wide- 

 spread. At all events the /"/t'ycw/wti antennae show — if we ignore one of 

 the short joints of the funicle which at any rate vary in number — entirely 

 the structure of a Melolontha , Rhopcca. Macrophylla, or Elaphocera anten- 

 nae : not only in the comparative difference in size of club, between (^ 

 and '^ , but also in the more iiuimate connection between the funicle 

 and club, by a gradual enlargement and unilateral broadening. Further, 

 in this, that the joints modified into the lamellate club vary — Rhoptra to 

 seven, five and three, Macrophylla fi\e and three, Pkocoma seven and 

 four-- in difteient species of the same genus ; and that as in Melolontha, 

 Anoxia, R/iopwa, Rhizolragus, Loihtiodcra et al, the lamellate joints aie 

 clothed at the edges — the first and last also at its free surface — with slilT 

 bristles. All these are peculiarities, which, partly by themselves, partly 

 in their combination, are characteristic of the Melolonthid antenna. 



Now as the situation of the stigmata in combination with the joroved 

 antennal structure, places Pleocoma primarily among the Meloh)7ithidii\ 

 so do other of its characters, as the structure of the mouth, the attenuated 

 tarsi, the dense woolly clothing of the breast, and the free, not connate, 

 ventral segments, point with entire certainty to the jmrticular systematic 

 position which is to be occupied by this genus. By all these characters 

 Pleocoma is referred to the group denominated Leptopodidce by Burmeister, 

 and more particularly to that part of it named Pachypodidi.e by Erichson. 

 The more comprehensive Leptopodidce which et]ual the Tanyproctini and 

 PacliypodidcP of Erichson are characterized by Burmeister precisely by the 

 slender tarsi and free ventral segments, and form in fact an equally natural 

 as well defined group. Within this group appear two modifications in 

 structure of mouth parts: on the one hand normally developed as in 



