it had been brought in a trading vessel from New Guinea: but it unfortunately died on its passage to England.

We feel happy, that in recording this new and beautiful bird, an early opportunity is given us of commemorating our deep sense of the kindness we received from a young naturalist of France, whose writings have already acquired celebrity, and who promises to inherit the great and commanding talents of his illustrious father. In prosecuting our studies at the Garden of Plants, we met with such unexampled liberality from its most distinguished Professors, that we feel embarrassed where first to return our thanks. But the facilities and attentions we received from M. Isidore Geoffroy Saint Hilaire, partly involved a sacrifice of personal convenience; uncalled for, either by the nature of his appointment, or by the common rules of courtesy. So much for the reception which British naturalists receive in France. We should do well, when striving to imitate the Zoological Institutions of that nation, if we imbibed somewhat more of their liberality. We hope the time is not far distant, when the system of regulations and restrictions, which now fence the Museum of a popular Society, from all who cannot pay for admittance, as members, may be exchanged for a policy more creditable to the age, and more honourable to the nation.

We shall offer a few remarks, illustrating this particular genus, in our next number.

Total length, 9 in.; wings 5; tail (beyond) 1½, from the base, 3½.

AMPULLARIA Pl. 1.
A. carinata.

AMPULLARIA carinata.

Carinated Apple-snail.

Family Ampullaridæ.—Guild.

Generic Character.

Specific Character.

In the first Series of our Illustrations, we endeavoured to lessen the confusion which, at that time, prevailed among the species of Ampullaria, figuring and naming such as appeared to us truly distinct. During the course of our labours, the sixth part of the "Animaux sans Vetebres" of the celebrated Lamarck was published in Paris; in which is described several species, figured in our volumes under other names. A want of mutual communication between authors writing at the same time, and on the same subject, has naturally caused confusion in nomenclature; which, at an early period, we intend to elucidate.

Our friend the Rev. L. Guilding, whose accuracy of observation can only be equalled by his indefatigable zeal, has established the distinction between the horny and shelly operculated Ampullariæ, on anatomical principles. The present species (which was engraved before his valuable memoir was published) must consequently be placed in his genus Pachystoma; while the carinata of Lamarck, from having a horny operculum, remains with the true Ampullariæ.

We know not the precise locality of our species; but conjecture it may be from some of the rivers of India.—Specimens, in different stages of growth, are in the Manchester Museum, and in our own.

UNIO Pl. 1.
U. truncatus

UNIO truncatus.

Truncated River Mussel.

Acephala Dimyaria.
Sub-family Les Nayades.—Lam.

Synopsis of the Genera.

Specific Character.

In our former Series, we have frequently mentioned the Fluviatile Bivalve Shells, of which the genus Unio appears to be the type. In a group which present so few certain characters, either for discriminating the species or characterizing the genera, we have, with other writers, held different opinions at different times. And the reader has only to peruse an interesting paper on these shells, in the Zoological Journal (Vol. I. p. 53), to be convinced of the intricacy of the subject.

Nevertheless it is observed, by those who study natural affinities, that when the links between two distinct forms of animals are so complete, that their dissimilarities are lost in intermediate and undefinable gradations, it is then that the natural arrangement is most likely to be discovered. For it has been demonstrated in such groups, that the most perfect order and harmony will come out, of what appeared an inextricable entanglement of relations. Such, however, will never result from the belief in a simple scale of Nature, or by attempting to circumscribe groups by absolute characters. We therefore now offer the foregoing sketch of the natural divisions of the Nayades, as the result of all we have seen or read upon this difficult subject.

We are unacquainted with any described species to which the shell here figured can be referred. Its substance is very thick, and its form nearly cylindrical. We have seen but one specimen, and that was with Mrs. Mawe.

White Breasted Wren.
Thryothorus Mexicanus.