188 Reviews. | Ji an. 
have hitherto been referring. By this memoir, entitled ‘ Contributions 
to an Insect Fauna, of the Amazon Valley,’ Mr. Bates has established for 
himself a high rank among original investigators, and has shown powers 
of observation of which he may justly feel proud. For although the 
subject of recurrent form, or analogical resemblance, or homomor- 
phism, or by whatever title it may be called, has attracted the atten- 
tion of many naturalists, the manner in which it is here illustrated in 
the Heliconine group of butterflies, is equally original and acute. 
Mr. Bates found that certain butterflies, so closely mocked cer- 
tain others belonging to distinct groups, that though always on the 
watch, it required all his caution to distinguish them.* He believes 
that these resemblances are intended as a protection to otherwise 
defenceless insects, by deceiving insectivorous animals, and pre- 
sumes that, seeing the excessive abundance of one species and the 
fewness of the individuals of the other, that the MHeliconide is 
free from the persecution to which the Leptalis is subjected ; and he 
seems inclined to attribute less to community of habit than we should 
be disposed to do, though it cannot be denied that such community is 
a constant concomitant of mimetism. 
The bearing of this subject, upon the origin of species, is plainly 
* The Heliconids appeared to him to be the objects mocked, because they all 
have the same family facies, whilst the analogous species are dissimilar to their 
nearest allies,—permitted, as it were, to produce the resemblance from the normal 
facies of the genus or family to which they severally belong. So close were 
the resemblances that Mr. Bates was never able to distinguish the Leptalides 
(Pieridze) from the species they imitated, without close examination after capture. 
And yet the Leptalides belong to a family totally different in structure and meta- 
morphosis from the Heliconidx, which they imitate. Moreover, they fly in the 
same part of the forest, and generally in company with the species they mimic. 
Species of Ithomia (Heliconidx) concerned in these imitations have all the character 
of true species, being distinct and constant. They are all excessively numerous 
in individuals, swarms of each kind being found in the districts they inhabit. The 
Leptalides are extremely rare ; they cannot be more than as one in a thousand of 
the Ithomiz. Moreover, none of these Leptalides have been found in any other 
district or country than those inhabited by the Ithomiw, which they counterfeit. 
A species very closely allied to L. Lysinoé has been received from Mexico; but an 
Ithomia of nearly tie same colours (I. Nero) also inhabits Mexico. Some other 
Leptalides exist which do not mimic Ithomix, but some other genera of the same 
family, as Methona and Mechanitis. ‘ A’similar series of mimetic analogies occurs 
in the Old World, between the Asiatic and African Danaidex (or representatives 
of the Heliconidx) and species of other families of butterflies and moths; but no 
instance is known in these families of a tropical species of one hemisphere counter- 
feiting a form belonging to the other.” So, also, on the banks of the Amazons 
parasitic. bees and two-winged flies mimic the dress of industrious and nest- 
building bees peculiar to this country, at whose expense they live, in the manner 
of the cuckoo. 
An examination of the beautiful coloured plates in the Linnean Society’s 
memoir shows that the mimetic resemblances exhibit a minute and palpably 
intentional likeness, which, as Mr. Bates expresses it, is perfectly staggering ; 
and no wonder, indeed, that he was constantly being deceived by them. Com- 
paring Leptalis Theonoé with Ithomia Flora, or the Ega variety with Ithomia 
Illinissa, Leptalis Amphione with Mechanitis Polymnia (both var. Egaensis), and, 
again, Leptalis Orise with Methona Psidii, we cannot fail to be astonished at the 
closeness of the resemblance, particularly when taken in connection with the 
normal form of Leptalis Nehemia. 
