80 EEOTYLIM. 



the Japanese islands alone ; in Western Europe there is only one, the well-known type 

 of the genus, T. Mpustulata, while America North of Mexico possesses about seven 

 typical species. 



The greatest difficulty exists in satisfactorily defining the genus, as very similar 

 insects are found in the Oriental region. These latter, however, are obviously not 

 typical. Throughout the Erotylidae, and especially in the ' Triplacides,' very minute 

 differences must be taken as of generic importance ; and if Tritoma is treated with the 

 same precision that the preceding genera have received, we must exclude various species 

 from Borneo, Ceylon, and other Tropical countries which have been referred to it. 



Tritoma is allied to Triplax by the shape of the raised part of the mentum, which 

 is, roughly speaking, trigonal ; it differs from it in its shorter form, being narrowed at 

 both ends, and by the consequently much shorter prosternum ; the latter is compressed 

 in front, thus causing its submarginal lines to converge in most species. In T. bipus- 

 tulata these lines terminate with a small inflexion, but in some species, as T. niponensis, 

 Lewis, the prosternal process forms a raised delta-shaped plateau. The club of the 

 antennae is short, with the three terminal joints connate, not perfoliate as in Triplax. 

 The tibiae are angularly widened, their apices being obliquely cut. 



M. Louis Bedel has, in his monograph of the Old- World species (L'Abeille, v. pp. 1- 

 50), given an exposition of the characters of both this genus and of Triplax, which 

 leaves little to be desired but the synthesis of the New-World species and of the 

 numerous others which have been added from Japan. With regard to the adoption 

 of the name Tritoma for this genus, I have given my view of the prescriptive right 

 which I think the consensus of naturalists for more than one hundred years has 

 established [cf. Notes from the Leyden Museum, vii. p. 257, note]. Its application to 

 the genus known to us as Mycetophagus is not justified by Geoffroy's use of it, in a 

 sense which was founded on an error, the name of course having reference to the 

 three-jointed club of the antennae. 



l. Tritoma dorsalis. (Tab. IV. fig. 20.) 



Breviter ovata, nigra, nitida ; ore, antennis (clava excepta), tibiis tarsisque luteis ; elytris punctato-striatis, 

 macula magna communi, extus attenuata interdum marginem attingente ; capite prothoraceque minu- 

 tissime parce punctatis, fere glabris. Long. 2% millim. 



Rah. Panama, Bugaba (Champion). 



This pretty little Tritoma is the smallest of its genus known to me and is also the 

 only one I have seen from a locality so far south or from within the tropics. It is 

 almost evenly oval, not more narrowed behind than in front ; the head and thorax 

 are smooth and shining ; the latter is rather convex (under a |~inch glass, covered 

 with small punctures), the base sinuate, the middle lobe fairly produced, the sides 

 finely margined, the basal edge plain. Elytra punctate-striate, the strial punctures 

 distinct, numerous, and small. Antennae about the length of the thorax, finely 



