149 



are not constant, and that the difference in the hind angles 

 of the prothorax is too slight to be rightly treated as specific. 

 The prothorax (and indeed the whole body) of submetallicus 

 is a trifle broader than that of Lindi, and to that perhaps is 

 due the slightly blunter appearance of the hind angles 

 when viewed from above. I am now satisfied that submetal- 

 licus is the female of Lindi. 



Group VI. 



The division of this Group into primary aggregates (A, 

 A A, and AAA) is very satisfactory. All the species in A 

 have hind coxae either fully as long as the 'metasternum, or 

 (if not quite so long) covering what I have called the 1st 

 ventral segment (it is really the 3rd, the basal two being very- 

 short and entirely concealed under the coxas), at least so 

 nearly that only its linear hind edging is visible. In A A the 

 hind coxae are in every instance notably shorter than the meta- 

 sternum. In all of them the portion of ventral segment ex- 

 posed beyond their hind margin is considerably more than the 

 mere linear hind edging. The species of AA have hind coxae 

 quite evidently (usually much) longer than the 2nd exposed 

 ventral segment, but two of them are near the border line 

 between A A and AAA, having the hind coxae so slightly 

 longer than the ventral segment in question that one has to 

 give more than a passing glance before being satisfied that its 

 place is in A A. Of these H. tridens, Blackb., differs notably 

 from all those that I have placed in AAA by the very much 

 coarser puncturation of its dorsal surface and the extremely 

 narrow middle lobe of the trilobed outline of its head ; and 

 H. nigellus, Er., in AAA would stand beside H. cawpestris, 

 from which it differs by the middle lobe of the trilobed outline 

 notably narrower, the antennae of dark colour, etc., etc. 



The character that I have used chiefly for breaking up 

 the primary into secondary aggregates is that of the punctura- 

 tion of the dorsal surface. I am not altogether satisfied with 

 this character for the purpose, inasmuch as there are species 

 near the border line of all the aggregates formed by its use, 

 but I have not been able to discover any more genuinely struc- 

 tural distinction by which more than much smaller aggregates 

 of species could be formed, and in dealing with so large a 

 number of species as those contained in this Group, it is in- 

 convenient to make the secondary aggregates numerous. For- 

 tunately, however, the Heteronycts do not appear to be vari- 

 able within the limits of a species in respect of puncturation. 

 I have carefully compared — in respect of a good many species 

 — the puncturation of numerous individuals taken in com- 

 pany and under circumstances that allowed no doubt of specific 



