442 Mr. S. 0. Eidley on Franz-Joseph-Land the mouth-parts, while in modern Diplopoda two segments are required for this purpose : this peculiarity of the fossil is in-ferred solely but sufficiently from the fact, perhaps even more remarkable, that every segment of the body (as represented by the dorsal plates), even those immediately following the single head segment, is furnished with tico ventral plates and bears two pairs of legs. As is well known, each of the segments im-mediately following the head-segments in existing Diplopoda bears only one ventral plate and only a single pair of legs — a fact correlated with the embryonic growth of these creatures., since these legs and these only are first developed in the young diplopod. The mature forms of recent Diplopoda therefore resemble their own young more than do these Carboniferous myriopods — a fact which is certainly at variance with the general accord between ancient types and the embryonic con-dition of their modern representatives, and one for which we can offer no explanatory suggestion worth consideration. Unfortunately the preservation of the appendages of the head in these Carboniferous forms is not sufficiently good in any that have yet been found to allow any comparison with modern types. This is the more to be regretted since these parts are those on which we depend largely for our judgment of the relationship of the Myriopoda to other Insecta and to Crustacea. If they were present and sufficiently well defined, we may well suppose that they would afford some clue to the genetic connexion of these great groups. The structure of the Carboniferous EuphohericB has thus been shown to differ so much from that of modern Diplopoda that, as stated at the outset, we seem warranted in placing them in a group apart from either of the suborders of modern Myriopoda and of an equivalent taxonomic value. Cambridge, U. S., January 7, 1881. XLVI. — Polyzoa, Coslenterata, and Sponges of Franz-Joseph Land. By Stuart 0. Ridley, B.A., F.L.S., Assistant in the Zoological Department, British Museum. [Plate XXI.] The specimens here to be described were collected by Mr. Grant, the naturalist accompanying Mr. Leigh Smith in his cruise last autumn to Franz-Joseph Land and Spitzbergen. They were presented by the latter gentleman to the British Museum, and form the first collection from the former locality which has yet
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