Dr. GRAY became Keeper of Zoology in 1840. Four years earlier, he had given to Sir Benjamin HAWES’ Committee a striking account of the condition of that department, illustrating it by comparisons with the corresponding Collections in Paris, which may thus (not without unavoidable injustice) be abridged:—The species of mammalia then in the Museum were four hundred and five; the species of birds were two thousand four hundred, illustrated by four thousand six hundred and fifty-nine individual specimens. At that date, the latest accessible data assigned to the Paris Collection about five hundred species of mammals, and about two thousand three hundred species of birds, illustrated by nearly six thousand specimens. The Museum series of birds was almost equally rich in the orders, taken generally; but in gallinaceous birds it was more than proportionately rich, a large number of splendid examples having been received from India. In the birds of Africa, of Brazil, and of Northern Europe, also, the Museum was already exceptionally well-stored. The special value of the Ornithological Collection undoubtedly showed that it had been more elaborately cared for than had been some other parts of natural history. But the extent and richness of the bird gallery, even at this period, is not to be ascribed merely to a desire to delight the eyes of a crowd of visitors. For scientific purposes, a collection of birds must be more largely-planned and better filled than a collection of mammals, or one of fish. In birds, the essential characters of a considerable group of individual specimens may be identical and their colours entirely different. [Sidenote: See _Minutes of Evidence_, 1836, p. 238.] Besides the numerous diversities attendant upon age and sex, the very date at which a bird is killed may produce variations which have their interest for the scientific student. The number of species of reptiles was in 1836 about six hundred, illustrated by about one thousand three hundred specimens. This number was much inferior to that of the Museum at Paris, but it exceeded by one third the number of species in the Vienna Museum, [Sidenote: _Ibid._, p. 242 (Q. 2996–9).] and almost by one half the then number at Berlin. The species of fish amounted to nearly a thousand, but this was hardly the fourth of the great collection at Paris, although it probably exceeded every other, or almost every other, Continental collection of the same date. Of shells, the Museum number of species was four thousand and twenty-five (exclusive of fossils), illustrated by about fifteen thousand individuals. This number of species was at par with that of Paris; much superior both to Berlin and to Leyden; but it was far from representing positive—as distinguished from comparative—wealth. There were already, in 1836, more than nine thousand known species of shells.