well-known and very common circumstance with regard to several groups of
animals. In our present researches there exists a remarkable example of this
fact in the genus Proctotretxis, consisting, as is now known, of at least fourteen
species, all inhabiting the w'estern coast of South America. These facts,
interesting as they are, have never been sufficiently investigated, although, it
must be confessed, there are so many anomalies in relation to this subject, th a t
we must despair of ever reducing the facts in question to any thing like fixed
laws.
The close approximation of the Eaniform and Hyliform groups of the
Anourous Amphibia is strikingly illustrated by several new forms obtained by
Mr. Darwin, whicli are so perfectly osculant between the two families, th a t it is
difficult to assign them a decided location. And the addition of some bufonine
forms in the family Ranid(B, as a t present constituted, and on the other hand of
some amongst the Bufonida, which are no less raniforra in their general structure
and habits, render it increasingly probable th a t the single character of the
presence or absence of superior maxillary teeth, must be considered as insufficient
to constitute alone a natural distinctive family character. There are
several minor points hearing upon the natural arrangement of the Anourous
Amphibians, which are illustrated by the characters of some of the species
now first described, which will doubtless at some future time assist in the
construction of a classification of these animals, bearing a t least a nearer
approximation to their natural arrangement than any th a t has hitherto been
promulgated.
The Ophidians have been placed in the hands of Mons. Bibron, who is
at the present time engaged in completing his admirable history of Reptiles,
by the publication of those volumes which are devoted to this order; and
it must be considered a fortunate circumstance that the delay which has
taken place in the appearance of that portion of his labours, has thus afforded the
opportunity of embodying in so perfect a work, the numerous discoveries of
Mr. Darwin in this particular department of Erpetology.
T. B.
Hornsey, Sept. 2, 1843.
L I S T O F S P E C I E S .
Alsodes montícola
Amblyrynchus cristatus
Demarlii
Ameiva longicauda .
Batrachyla leptopus
Borborocsetes Bibronii
------------------ Grayii
Bufo Chilensis .
Centrura flagellifer
Cyclodus Casuarinee .
Cystignathus Georgianus
Diploleemus Bibronii
--------------- Darwinii
Gerrbosaurus sepiformis
Gymnodactylus Gaudicliaudii
Hyla agrestis .
Vauterii
Ilyloriiia sylvatica
Leiocephalus Grayii
Leiuperus salarias
Limnocliaris fuscus
Litoria glandulosa
Naultinus Grayii
FAOB
. 41
23
. 22
28
. 43
35
. 36
49
. 25
50
. 33
21
. 20
29
. 26
46
. 45
33
42
27
Pliryniscus nigricans
Pleurodema bufoninura
------------- Darwinii
------------- elegans
Proctotretus Bibronii
------------- Cliilensls
------------- cyanogaster
------------- Darwinii
---------------Pitzhigetii
-------------gracilis
Kingii .
multimaculatus
nigromaculatus
pectinatus .
------------- pictus
------------- siguifer
------------- tenuis
------------- Weigmannii
Pyxicepbalus Americanas
Eana Delalandii .
Mascariensis .
Rhinoderma Darwinii .
Uperodon ornatum
36
37
6
2
12
40
31
32