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 



