PROTECTIVE MIMICKY. 221 



belonging to the genus Qiimmdia which imitates, as many 

 SesiidfB do, a humble bee. The only objection to regarding 

 this as a question of mimicry is the rather important one, that 

 no humble bees exist where the moth does. Dr. Seitz, how- 

 ever, suggests, not, as Mr. Scudder has, that the mimicked 

 form did exist, but has died out ; but that the moth has mi- 

 grated from some country where humble bees are found. The 

 suggestion is, however, and naturally, put forward very doubt- 

 fully. There is clearly no a prio)'i objection to it, particularly if 

 the larva feeds in the interior of stems which are constantly 

 imported and exported, but it must as clearly remain a 

 suggestion for the present— an alternative suggestion to the 

 hypothesis that the mimicked form has died out. 



Cases of Apparently Useless Mimicry. 



1 am indebted to Dr. David Sharp, F.R.8., for a curious 

 instance of resemblance between two British beetles, which 

 appears at iirst sight to conform to all the conditions of true 

 mimicry. 



Cceliodes didymus is a minate beetle, very common upou 

 nettles ; with it is occasionally found a rare species, Ceatho- 

 rhynchus urticce ; these two insects .are so much alike, that it 

 needs a careful investigation to distinguish them. And yet, 

 what advantage is got by this resemblance ? Supposing that 

 the common species is nauseous in taste, — it cannot well possess 

 any other adequate defence, and this has not been proved, — its 

 very minuteness would seem to render any detailed mimicry 

 more than necessary ; and yet this exists. 



A Swedish naturalist. Dr. Carl Bovallius, has lately de- 

 scribed * a remarkable species of amphipod crustacean which 



* ynm Acta Reg. Sue. TJpsala, 1885. 



