— 202- 



On the Position of the Genus Pleocoma, Lee, 

 in the Lamellicorn System. 

 My Dr. Gerstaeker. 



It is sufficiently well known that those related forms termed families, 

 as well in the Insects as in the other divisions of animal life, range them- 

 selves in larger, more sharply defined groups ; sometimes easily, an I 

 sometimes only with the greatest difficulty. The latter occurs naturalh 

 where all the members of a large group have essentially the sarrn 

 and life habits, while the former is more usual when differences in habit 

 bring about modifications of structure, which afford characters valuable 

 in systematic classification. In the Coleoptera for instance, the Lamelli- 

 cornia would be classed among those, which, sharply defined as they an 

 from others, would admit of a much more ready and satisfactory division 

 into naturally defined groups, than in say the families ofahe Elaieridce, 

 Biiprcstuke, or even the Carabid(£, Melasomidce and Cerambycidce. WhiW 

 in the latter group the case can readily occur— in fact has repeatedly oc- 

 curred — that a newly discovered genus offers so many and so variouslj 

 combined characters, that the exact position and relationship will be dif- 

 ferently determined according as the student values the often very obscure 

 and subordinate structural characters, such doubts scarcely exist at all in 

 a family like the Lamellicoms, or at least confine themselves to such 

 isolated genera which as for instance Pantodinus and Euchirus are so near 

 to the border line between two nearly related groups, that they might 

 with almost equal justice be referred to either. When therefore the case 

 does exceptionally occur, that in such a family a newly discovered genus 

 is, by an able and careful student, entirely misapprehended as to its 

 relationships, the reason is clearly to be sought in the fact that in such a 

 type the subordinate or habital peculiarities predominate and obscure 

 and crowd out of view the essential characters to such an extent that 

 they are entirely overlooked. 



The extraordinary genus Pleocoma, described by Leconte in 1S56. 

 became known to me in 1866 in a single example in the collection of the 

 Berliner Kntomologische Museum, and aroused in me, even at that time, 

 the gravest doubts as to the correctness of the position assigned to it by 

 Leconte as a near relative of the Geotrypini; but I was unable at that time 

 to oppose that view from the examination of a single specimen which 

 also lacked the antennae— so highly important in classification. 1 might 

 have done so successfully in 1872 or '73 when a second, perfect example 

 ol Pleocoma fimbriata came into the possession of the Berliner Museum 

 from the well known Californian traveler Alphons Forrer, but was pre- 



