313 

 COLYDIID^. 



DITOMA. 



A large number of species have been attributed to this genus 

 which have since had to be removed from it and formed into 

 distinct genera. The number of these is so great that without 

 access to a large collection of the Colydiidce of the world it is 

 impossible to deal satisfactorily with the generic apportionment 

 of the Australian species at present standing under the name 

 Ditoma. According to Lacordaire the essential characters of 

 Ditoma in the "Tribe" Synchitides are as follows " Basal 3 joints 

 of tarsi equal or nearly so inter se, tibipe not spinous externally 

 but armed with a small apical spine, all the tarsi four-jointed, 

 mandibles bidentate at apex, the ventral segments all emargiaate 

 behind, head devoid of antennal sulci, club of antennae two- 

 jointed, sides of prothorax narrowly margined. Of the characters 

 above mentioned that based on the form of the hindmargin of 

 the ventral segments does not appear to me to be founded on 

 correct observation. I have before me specimens of the European 

 D. crenafa, Hbst. (the type of the genus) and cannot find that 

 its ventral segments are emarginate behind, or differ noticeably 

 in outline from their form in allied genera. Nor do I find that 

 authors subsequent to Lacordaire make any use of this character. 

 In spite, therefore, of the great weight of I^acordaire's authority 

 1 think this character must be dropped. Applying the other 

 characters assigned by Lacordaire strictly I cannot find any 

 described Australian Colydiid which is a true Ditoma In the 

 absence, however, of assurance that I have before me the diag- 

 noses of all the described genera closely allied to Ditoma I do not 

 feel justified in proposing new generic names for those which do 

 not fall into any already named genus known to me, and there- 

 fore must leave them provisionally in Ditoma. As I have before 

 me authentic specimens (in every case but 'jviq, the type) of all 

 the Australian species except one that have been described as 

 Ditoma I may perhaps advantageously furnish some notes on 

 them : 



D. serricollis, Pasc, is the only species of which I have not an 

 authentic example. Its author does not enumerate its structural 

 characters in detail but says that " as far as external characters 

 go" it is certainly a Ditoma. So many genera near Ditoma have 

 been established since the date (1860) of that note that it cannot 

 now be taken for more than a statement that the insect is a 

 Ditoma rather than a member of any other then known genus. 

 It appears to me to be probably identical with linentocolliSy 

 Blackb., which some years ago M. Grouvelle (a specialist on the 

 Colydiidce) informed me that he considered E had done right in 

 acing in Ditoma. Its description is not sufiiciently detailed to 



