Specimens of chert-rock from the Productus-chert division of the Permo-Carboniferous series of Spitzbergen are shown to consist largely of detached siliceous sponge spicules, thus indicating the probable derivation of this rock from the skeletal remains of these organisms. The chert is of the same character as that of the Yoredale beds of the British Isles, and it occurs on the same relative geological horizon. The Productus-chert division has a thickness on Axel's Island of 376 m., of which 265 m. are chert, and 111 m. dark siliceous schists, likewise containing sponge remains, but less abundantly than the chert. The chert had previously been regarded as connected in some way with the igneous rocks of the island.

Of this I have seen only two specimens. One of them, slightly longer than the other, measures 3½ inches in length up to the commencement of the caudal fin, which is deficient in both; the greatest depth of the body ½½ inch, the length of the head nearly the same. The dorsal fin is opposite the interval between the ventral and the anal; both dorsal and anal are triangular acuminate in shape, with delicate rays which at first are somewhat distantly articulated, the joints being ornamented with one or two longitudinal sulci. The pectorals are not seen in either specimen, but the smaller of the two shows a well-preserved ventral, which is pretty large, and acuminate in shape.

In the Thirty-Sixth Annual Eeport on the New York State Museum of Natural History (8vo. Albany, 1884), is a folding plate with a fly-leaf descriptive of a specimen with peculiar structure from the Calciferous Sandstone group of Greenfield, Saratoga Co. referred to a new genus and species under the name of Cryptozoon proliferum, but no author's name appeared to either the plate or the description. The peculiar appearance of the American figure reminded Prof. Eupert Jones of a specimen in his collection, and having kindly placed it in ray hands and permitted me to bring it before the notice of the readers of the Geological Magazine, he has given it to the British Museum. Prof. Jones's specimen was collected by the late John Calvert, F.G.S., the author of “Vazeeri Rupi, the Silver Country of the Vazeers in Kulu,” and the rock is referred to at p. 8 of that book. The specimen was shown by Mr. Calvert to Sir Warington W. Smyth (whose opinion as to its inorganic nature is quoted by Mr. Calvert), and afterwards given to Prof. Jones.

A Small series of rock-specimens, consisting chiefly of fragments of basalt, dolerite, volcanic conglomerate and tuff, which were collected near Kilima-njaro, by F. Holmwood, Esq., C.B., lateConsul-General at Zanzibar, was recently forwarded to the Museum at Jermyn Street, and placed by Dr. A. Geikie in my hands for determination. Among these specimens was a small block, the crystalline texture and high density of which at once arrested attention Freshly fractured surfaces of this rock present numerous glistening facets, which with the aid of the pocket-lens are seen to be the cleavagefaces of a yellowish-green, a dark-green, and a garnet-red mineral. These minerals are respectively olivine, hornblende, and hypersthene in nearly equal proportions, the hornblende being perhaps slightly predominant. They form a holocrystalline granular aggregate, in which the.grains are of nearly equal size and without crystalline contours; in other words, the structure is allotriomorphic-granular. Subordinate both in size and quantity to the three principal constituents is magnetic iron-ore.

I.—To avoid useless repetitions, I shall consider as admitted what I have said in my paper “Sur le genre Euclastes,” especially:

1. Euclastes, Cope = Chelone, Owen (non Ritg.) (pars) = Lytoloma, Cope = Puppigerus, Cope (pars) = Glossochelys, Seeley = Pachyrhynchus, Dollo = Erquelinnesia, Dollo.

In the first paper of this series were described several dykes from the shores of the Menai Straits, belonging apparently to one system of intrusions, and some of them cutting Carboniferous strata. Their precise age, however, can be fixed only on the supposition that they may fairly be correlated with certain post-Carboniferous but pre-Permian dykes in the Anglesey Coal-field. These latter rocks have a strong general resemblance to the Menai Straits dykes, and as they are by no means easily accessible, they will not be described in detail. Only one will be selected, as offering a rather pronounced type: the specimen is from the Henslow collection.