376 Jenkins and Duncan on the genus Palceocoryne 



In later Tertiary times the world had much the same continental 

 contours as at present ; but with vacillations, letting in the Grlacial 

 and Pluvial periods, when ice and water exerted their utmost power 

 in modelling the northern hemisphere at least, and produced the great 

 banks of gravel, and coatings of boulders and clay, that mask so much 

 of its rocky surface. To the existing deltas, marshes, turbaries, 

 lakes, glaciers, and river-systems, with their often subterranean 

 streams, we need only refer as examples of the natural machinery by 

 which fresh water acts in modifying the surface now, and has acted 

 in times past, as shown by this brief sketch of the primeeval rivers 

 of Britain. 



II. On PALM0G0R7NE A GENUS OF TUBULARINE HyDKOZOA PEOM THE 



Carbonifekous Formation. 



By P. M. Duncan-, F.E.S., Sec. Geol. Soc, and H. M. Jenkins, F.G.S., Sec. Royal 



Agric. Soc. 



(Phil, Trans, for 1869, pp. 693-699, pi. Ixvi.) 



THE remarkable little organism which forms the subject of this 

 paper, was obtained from the lower shales of the Carboniferous 

 limestone series of Ayrshire and Lanarkshire, so rich in fossil 

 Brachiopoda, Polyzoa, Crinoidea, and Madreporaria ; and was found 

 attached to the margins of the polyzoarium of FenesteUce, and also 

 in a detached and more or less fragmentary condition amongst the 

 small pieces of broken Polyzoa, and Crinoid stems which compose 

 the fossiliferous layers of the shales. 



The base of Palceocoryne was expanded, giving rise to a short 

 robust and cylindrical stem fluted and punctated on its surface, and 

 surmounted by the body of the polypite from the upper margin of 

 which radiate a single whorl of long and slender tentacles. On the 

 upper surface of the body, a crateriform process with an opening 

 on its apex, indicates the position of the mouth. 



Its external investment appears to have been calcareous, covering 

 the whole of the hydrozoon, except at the opening for the mouth 

 and the terminations of the tentacles which had probably ciliated 

 ends projecting beyond the periderm or polypary. 



This is an almost solitary instance of a Hydrozoon having a hard 

 periderm, save the recent genus Bimeria, discovered on the West 

 coast of Ireland by Dr. T. Strethill Wright. 



The Zoological position of the fossil is amongst the Hydrozoa in 

 the order Tubularidas, and near the Eudendridee. Two species are 

 described and figured by the authors Palceocoryne Scoticum and P. 

 radiatum. 



III. — The American Journal of Science and Arts, Vols, xlviii. 

 AND XLix. Contains the following communications from Prof. 

 0. 0. Maksh, of Yale College. 



I. Notice of some new Mosasauroid Beptiles from tlie Greensand 

 of New Jersey. — A striking difference between the reptilian fauna of 

 the Cretaceous of Europe and America, is the prevalence in the 



