Hymenoptera aculeata from Majorca and Spain. 647 
the manner suggested above (Trans. Ent. Soc. 1902, pp. 
386, 387). 
I cannot doubt that a closer attention to the facts of 
mimicry in the Aculeates would long ago have revealed 
the insufficiency of the Batesian hypothesis and the 
necessity of that to which Fritz Miiller was driven in 
1870. The group on Montserrat may be compared in the 
closest manner with the synaposematic Neotropical Rho- 
palocera. The central species, belonging to the genus 
Sphecodes, represent the Jthoming, usually the dominant 
members of the South American groups. The genera 
Halictus, Nomada, and Osmia, similarly represent the 
convergent Lycorea, Heliconius, and Actinote; while the 
fly Ocyptera may be to some extent paralleled by a Hetero- 
cerous mimic, such as Pericopis or Castnia. 
As regards both groups we may feel the same confidence 
that the Miillerian explanation of common warning colours 
accounts for nearly the whole of the facts: as regards both 
the same uncertainty as to whether some outlying member, 
such as the fly in one or Casinia in the other, may not be 
a real (Pseudaposematic) mimic in the Batesian sense. 
In both groups the fact lost sight of by Bates is equally 
evident, viz. that the mimicry is closest between those 
members whose special defence is clearest—that just as 
the mimicry of Ithomiine by Heliconine far transcends the 
resemblance borne to the former by Danaine, Nymphaline, 
Pierine, or moth, so the likeness of other Aculeate genera for 
Sphecodes far surpasses that borne by the mimetic Dipteron. 
In fact, Mr. Saunders speaks of the similarity between the 
females of some of the small southern species of Halictus 
and Sphecodes being so great that he has often to look for 
structural characters at the apex of the abdomen in order 
to decide upon the genus. In speaking of this remarkable 
resemblance the great Hymenopterist, indeed, suggests the 
probability that Halictus and Sphecodes arose froma single 
stock at no distant date. But, however recent this period 
may be, it is highly improbable that superficial likeness 
in colour and pattern can be its heritage, inasmuch as 
a safe distinction can be established by an appeal to 
comparatively deep-seated structural characters. 
This interesting group is only a section of a very 
large assemblage of Aculeates characterized by a black 
ground-colour, and the development of more or less red 
on the abdominal segments. Mr. Saunders has kindly 
