163 



from fasciculatus, but I do not think it likely to be sambucinus, 

 Boisd., as the habitat of the latter is presumably the neigh- 

 bourhood of Sydney, where I have taken an Artec-cents perfectly 

 distinct from (though closely resembling superficially) fasciculatus, 

 and which I have little doubt is the true sambucinus. 



The species of this genus are very difficult to deal with on 

 account of their pubescence being extremely easily rubbed off, 

 — so that it is necessary to rely almost entirely on structural 

 characters for identification and the descriptions of markings 

 can be but little trusted for identifying any but very fresh 

 specimens, — and also from the absence (alluded to by M. Lacor- 

 • daire) of any readily available character for determining the 

 sex of a specimen. In studying a considerable number of 

 examples of Arceocerus from widely separated parts of Aus- 

 tralia I find, owing to the difficulties mentioned, a certain 

 number of forms which I believe to represent additional 

 species, but which I hesitate to treat as certainly distinct, and 

 in the following pages I have limited myself to the well-marked 

 species. 



The characters of some of the Arceoceri described below do not 

 altogether agree with Lacordaire's diagnosis of the genus, but I 

 am satisfied that the characters in question are not truly generic. 



The following tabulation will assist in the determination of 

 the Arceoceri known to me as Australian. 



A. Each elytron having a well developed basal crest bicristatus, Blackb. 

 A A. Elytra even at the base, — or nearly so. 



B. Ninth joint of antennae not or scarcely longer 

 than tenth. 



C. Legs dark .... Koebelei, Blackb. 



CC. Legs of pale colour ... ... fasciculatus, DeG. 



BB. Ninth joint of antennae notably longer than 

 tenth. 

 C. Antennas long enough to reach the base of the 

 prothorax. 

 D. Antennal club moderately robust (about as 



much so as in D pestilens, OllifF) . . . sambucinus, Boisd. 



DD. Antenual club notably more slender ... lindensis, Blackb. 

 CC. Antennae not long enough to reach base of 



prothorax asperulus, Blackb. 



.A. bicristatus, sp. nov. Ovalis, minus latus ; sat convexus ; 

 picea, pube lsete brunnea dense vestita, hac pube cinerea et 

 nigricanti variegata (hac in pronoto ad latera et medium et 

 in elytris maculatim, ilia in elytris sparsissime maculatim, 

 dispositis) ; antennis prothoracis basin attingentibus, tes- 

 taceis, clava fusca, articulo 9° quam 10 us vix longiori ; pro- 

 thorace minus fortiter transverso, antice fortiter angustato, 

 lateribus leviter arcuatis, basi bisinuata, supra crebre aspere 

 punctulato, angulis posticis acutis ; elytris crebre aspere 



