SHELLS ABOYE THE PRESENT LEVEL OF THE SEA. 353 



this remarkable fact, that the ocean-floors present a uniformity of 

 level which corresponds with that of our most level and extensive 

 continental plains." This may be so ; the ' Challenger ' soundings 

 were necessarily few and far between; but the numerous and 

 close-set soundings lately taken for the new submarine telegraph- 

 cable from Yalentia to XewfoundlaHd tell quite a different tale, and 

 serve to show the extreme unevenness of the ocean -floor in the 

 Korth Atlantic, to say nothing of the depth of 748 (between 1168 

 and 1260 fathoms) ascertained by the ' Bulldog ' soundings, and of 

 690 (between 1450 and 1230 fathoms) in another part of the same 

 ocean, ascertained by the ' Valorous ' soundings. More data would 

 certainly be desirable. 



Mr. Murray, one of the ' Challenger ' naturalists, and who has 

 especially studied the oceanic deposits, gave at Manchester, in 

 December 1877, two admirable lectures on- the physical and 

 biological results of that Expedition, and expressed his belief that 

 the ocean-basins are of "vast antiquity," but that " on the whole 

 they have been areas of subsidence." Tha'word " antiquity " is, of 

 course used relatively to the question of the time occupied in the 

 subsidence, which we have no means of ascertaining or even 

 guessing. 



It may be said that Sicily has long been the seat of intense 

 vBlcanic energy ; but has not every other part of the world been in 

 its turn also subject to similar action ? 



I append a list of the marine organisms which have been found 

 on Moel Tryfan by Mr. Trimmer, Mr. Darbishire, Capt. Drury Lowe, 

 Professor Eamsa,y, Mr. Etheridge, Mr. Bateson (the proprietor of the 

 Alexandra slate-quarries), and Mr. Mackintosh. The specimens col- 

 lected by Mr. Trimmer are in the Museum of this Society ; and 

 other specimens are in the Museum of Practical Geology. I have 

 examined all the specimens — except some of those included in 

 Mr. Darbishire's list, which I will give in italics. 



MOLLrSCA. 



CONCHIFERA. 



Ostrea edulis, Linne. 



Pecten opercularis, L. 



Mytilus edulis, L. 



M. modiolus, L. 



Leda pernula, Miiller. 



Pectuncidus gJycymeris, L. 



Cardium echinatum, L. 



C. fasciatum, Moutagu. 



C. edule, L. 



C. norvegicum, Spengler, 



Cjprina islandica, L. * 



Astarte sulcata, Ba Costa ; and var. eUiptica. 



A. borealis, Chemnitz. 



A. crenata, Gray ("crebricostata," Forbes). 



A. compressa, Mont. 



Venus exoleta, L. 



Tapes virgineus, L, 



•Q-J.G.S. No. 143. 2 b 



