316 Mr. T. V. Wollaston on the CoJeo2)tera of St. Helena. 



were evidently the opposite sex of tlie smaller form — though^ 

 at the same time, if males (as their comparatively armed cly- 

 peus would imply them to be), I should have been driven to 

 the anomalous conclusion that the individuals of that particular 

 sex were the larger and less brilliant of the two ! and more- 

 over, on examination, so many other characters presented 

 themselves that I began to feel doubtful whether they were 

 not, after all, specifically distinct. I therefore sent two of them 

 to Mr. C. O. Waterhouse, of the British Museum, who has 

 lately paid considerable attention to the Lamellicorns, and he 

 is decidedly of opinion that they cannot be referred to the 

 same species as the other examples which I forwarded to him. 

 Indeed Mr. Waterhouse has shown by dissection that these 

 two opake ones are males ; and as I have myself since opened 

 the abdomen of the third, as well as those of eleven out of the 

 12 brighter individuals, and find them all to be males likewise ! 

 there can be no longer any qiiestion that the two are positively 

 distinct*. 



Assuming therefore that the above opinion is correct (and 

 it is difficult to see how it can be otherwise), the M. adumbratus 

 recedes from the eudoxus in being more opake and (on the 

 average) a little larger, in its sculpture being altogether shal- 

 lower and less rough, in its frontal tubercle (though I can 

 only vouch for the male sex) being veiy much more developed, 

 in its clypeus being narrower, more coarsely margined at the 

 sides and more recurved at the tip, in its anterior prothoracic 

 angles being rather more porrect and acute, and in its elytra 

 {none of the punctures of which have apparently any decided 

 tendency to be longitudinally distribiited in obsolete flexuous 

 evanescent grooves) being more straigJdhi truncate behind (or 

 with the sutural angles less rounded-oft"), so as to expose a 

 portion of the propygidium — which is itself more triangular 

 (or pointed in the centre), instead of being separated from the 

 ])ygidium by a straight suture, and is likewise roughened all 

 over (very densely so in the middle) with short transverse 

 plaits or tubercles (well separated from each other) whicli 

 clearly are employed by the insect for the purposes of stridula- 

 tion. This stridulating-powcr is very important ; and I doubt 

 whether the preceding species can stridulate (at any rate 

 audibly so to us) at all ; for its propygidium, which is entirely 

 concealed by the apical portion of the elytra, is com^Htrativeh/ 

 bright and unscul])tured, an extremely few and distant trans- 

 verse pUxits in the liinder central region being alone traceabk\ 



* The twelfth of tliese more polished examples was imperfect, and 

 had lost its ahdomeii ; but it diil'eied in no respect, thai I could perceive, 

 from the rest. 



