1877.] 143 



ANCHOMENID.E. 



More than tliree-fourtlis of the Geodrphaga that have occurred to 

 me on these islands belong to this family. Among the species that I 

 am about to describe, I think it not impossible that there may be 

 found eventually material for some new genera ; but it does not appear 

 to me that those of which the characters have been already published are 

 in so settled a state, as to render the formation of new genera (unless 

 very strongly marked) likely to be of permanent value, until the 

 species already existing in collections have been more comprehensively 

 studied, and the result published. 



My species possess in common the following characters (besides 

 those shared by the whole group Anchomenidce) : "mentum with a 

 central tooth, lahrum not emarginate, antennce with 3rd joint not more 

 than moderately longer than 4<th., prothorax cordiform or suborbicular, 

 elytra moderately sinuate at extremity, claios simple." 



There are some eight or ten genera already characterised posses- 

 sing these characters, many of them closely allied, all of them grouped 

 around, or actually taken out of, the two extensive genera Anchomenus 

 and Di/scohis. As I cannot identify my species with any of the 

 smaller genera, and can discover no strongly marked character sepa- 

 rating them from the larger ones, I think it better to assign them all 

 to the two leading genera. But here a difficulty presents itself. 

 Anchomenus and Dyscolus run into each other very remarkably. The 

 principal accepted distinctive characters are, I believe, as follows : In 

 Di/scolus, the 4th joint of the tarsi should be bilobed (in Anchomenus 

 not more than moderately emarginate). Dyscoliis, also, should have 

 the parallel depressed form of a Droviius (near which genus Dcjean 

 placed it), but without any truncature of the elytra, and should occur 

 on the leaves of plants. 



These characters, however, do not seem to be invariably found in 

 company (I see tlie fact is alluded to by Lacordaire in his Gen. des 

 Col.). 



In some of the species I am about to describe, there is this un- 

 satisfactory want of exactness in possessing the distinctive characters 

 of either Di/scolus or Anchomenus ; some leaf-frequenting species, with 

 bilobed tarsi, being of at least moderately convex form, and some 

 having the 4th j.oint of the tarsi less deeply and widely bilobed than 

 others ; while among the ground-frequenting convex species, some have 

 the tarsi almost bilobed. All those, however, which I describe as Di/s- 

 colus, occur on leaves of plants, and have the 4th joint of the tarsi (in 



