292 Zoological Society : — markings is so wide (as is proved by the gradational transitions which present themselves between what at first sight appear to be widely-separated types), that only where some very decided and con-stant difference of internal conformation presents itself, will it be safe to assume a specific diversity. In one case, in which he had thought that a certain series of specimens was sufficiently distinguished by its peculiar physiognomy from the rest, residual forms presented themselves which could not be with certainty assigned to either type, so completely do they link together the two by the softening down of the peculiarities of each. And a yet more remarkable link of connexion is established by examples collected on the coast of Japan by the American expedition to that country, in which the most distinctive characters of each type are curiously combined. Closely related to Operculina is another genus, Amphistegina, which bears an equally near resemblance to Nummulites, though it has been completely separated from both in the classification of M. d'Orbigny, who has placed it in a distinct order, Entomostegues, on account of the unsymmetrical form of its shell and the alternating disposition of its chambers. But the author has found, from an extensive comparison of individuals, that this want of symmetry is so little constant, as to be altogether valueless in a systematic point of view, many specimens being perfectly symmetrical, whilst others are very far from being so, and every gradation presenting itself between these two extremes. The most common among existing species is the Amphistegina gibbosa, which is very extensively dif-fused through the tropical ocean, and which, though generally of small size, acquires in the Philippine region dimensions nearly equal to those of the fossil Amphistegina of the Vienna and other tertiary deposits. But Mr. Cuming's Philippine collection contains another and far larger species, which is distinguished by the extraordinary thinning-out of the last whorl ; and it is remarkable that in this species the canal-system is highly developed, although completely absent in A. gibbosa, — a difference of structure, which, being asso-ciated with a very close resemblance in external aspect and general conformation, seems only to be accounted for on the supposition that the difference in size requires a difference in the arrangement of the nutrient apparatus. ZOOLOGICAL SOCIETY. March 9, 1858.— Dr. Gray, F.R.S., V.P., in the Chair. Proposal to separate the Family of Salamandrid^e, Gray, into Three Families, according to the form of the Skull. By Dr. J. E. Gray, F.R.S., V.P.Z.S., Pres. Ent. Soc, etc. In the Catalogue of Amphibia in the British Museum I placed all the Salamanders which have teeth on the inner side of the hinder edge of the palatal bone together in a single family, under the name of SalamandridcB.
BioStor
