The Challenger has explored the Antarctic seas in a region intermediate between those examined by Sir James Ross’s expedition; and the observations made by Dr. Wyville Thomson and his colleagues in every respect confirm those of Dr. Hooker:—­

“On the 11th of February, lat. 60 deg. 52’ S., long. 80 deg. 20’ E., and March 3, lat. 53 deg. 55’ S., long. 108 deg. 35’ E., the sounding instrument came up filled with a very fine cream-coloured paste, which scarcely effervesced with acid, and dried into a very light, impalpable, white powder.  This, when examined under the microscope, was found to consist almost entirely of the frustules of Diatoms, some of them wonderfully perfect in all the details of their ornament, and many of them broken up.  The species of Diatoms entering into this deposit have not yet been worked up, but they appear to be referable chiefly to the genera Fragillaria, Coscinodiscus, Choetoceros, Asteromphalus, and Dictyocha, with fragments of the separated rods of a singular silicious organism, with which we were unacquainted, and which made up a large proportion of the finer matter of this deposit.  Mixed with the Diatoms there were a few small Globigerinoe, some of the tests and spicules of Radiolarians, and some sand particles; but these foreign bodies were in too small proportion to affect the formation as consisting practically of Diatoms alone.  On the 4th of February, in lat. 52 deg., 29’ S., long., 71 deg. 36” E., a little to the north of the Heard Islands, the tow-net, dragging a few fathoms below the surface, came up nearly filled with a pale yellow gelatinous mass.  This was found to consist entirely of Diatoms of the same species as those found at the bottom.  By far the most abundant was the little bundle of silicious rods, fastened together loosely at one end, separating from one another at the other end, and the whole bundle loosely twisted into a spindle.  The rods are hollow, and contain the characteristic endochrome of the Diatomaceoe.  Like the Globigerina ooze, then, which it succeeds to the southward in a band apparently of no great width, the materials of this silicious deposit are derived entirely from the surface and intermediate depths.  It is somewhat singular that Diatoms did not appear to be in such large numbers on the surface over the Diatom ooze as they were a little further north.  This may perhaps be accounted for by our not having struck their belt of depth with the tow-net; or it is possible that when we found it on the 11th of February the bottom deposit was really shifted a little to the south by the warm current, the excessively fine flocculent debris of the Diatoms taking a certain time to sink.  The belt of Diatom ooze is certainly a little further to the southward in long. 83 deg.  E., in the path of the reflux of the Agulhas current, than in long. 108 deg.  E.