Royal Physical Society. 107 



behind ; the posterior angles sometimes a little pointed *, 

 the posterior margin straightly truncate, and only towards the 

 middle very slightly sinuated. It is covered with a yellow silken 

 pubescence. The elytra, as well as the whole body, are black ; 

 they have a brownish-blue or purplish peachy bloom, with a 

 yellowish pubescence more conspicuous at their base and basal 

 margins than on the disk. They are finely punctured, very im- 

 perceptibly striated, longish oval, in the middle a little widened, 

 behind obtusely acuminate. The legs are ferruginous red, the 

 posterior thighs sometimes brownish. 



This is the first of a little group of species, which, with a de- 

 cided yellow pubescence on the thorax, has a brownish-blue or 

 purplish bloom on the elytra, accompanied with yellow hairs or 

 pubescence conspicuous along the base and basal margins of the 

 elytra, — a character which will limit our comparison to only two 

 or three species. The two species just described, C. coracinus 

 and C. morio, have also yellow pubescence on the thorax, but 

 their elytra have not a purplish bloom, but a greyish- ash bloom, 

 and want the yellow hairs along the base. The yellow pubes- 

 cence on the thorax of these two also is feeble both in colour and 

 consistence compared with those which follow. The form of 

 the thorax of this species distinguishes it from all 

 the others. Figure 13 shows the relative form 

 of the thorax of nigrita and tristis, the plain line 

 being the outline of nigrita, and the dotted line 

 that of tristis. These two species are in other 

 respects extremely alike. The antennae however 

 also furnish characters of discrimination — the club of tristis being 

 short, heavy and thick, while the antennae of nigrita are long and 

 thin and only obsoletely clubbed. The great breadth of the thorax 

 of grandicollis, Erichs., easily distinguishes it ; and the form of the 

 thorax oirotundicollis, Kelln., which is an exaggerated form of that 

 of tristis as above delineated (fig. 13), will prevent nigrita being- 

 confounded with that species or variety. The elytra in both ni- 

 grita and tristis are elongate, and give them a longer character than 

 rotundicollis, which has the elytra short and rapidly acuminate. 



* Erichson in his description states that the posterior angles are pointed, 

 but Kraatz says that he cannot agree with him in that respect : — " accord- 

 ing to my view," he says, " they are right-angled, in not a few examples 

 passing into obtuse-angled." I have examined a considerable series 

 carefully with a view to determine this point, and find that both are 

 right. I possess specimens which have the posterior angles pointed, and 

 others where there is no appearance of a point, but the line of the base of 

 the thorax perfectly straight. This is another proof of the variable cha- 

 racter of the genus. It also shows us how inadequate are Spence's sec- 

 tional divisions which are founded on this very character. 



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