546 J. S. Gardner — The Permanence/ of Continents. 



ventrals and anal, and is of considerable size, its height being 2|- 

 inches, and equal to the extent of its base ; its form is triangular, 

 and sharply acuminate. The anal fin commences opposite the 

 middle of the base of the dorsal, and, unlike what is usually the 

 case in Eloniclithjs, differs decidedly in shape from the last-named 

 fin, and comes to resemble the anal of Pygoptenis, in being pro- 

 longed backward in a fringe-like manner. Anteriorly, the fin is 

 sharply acuminate, its longest rays being about 2 inches in length ; 

 behind the apex its contour rapidly falls away, till about two inches 

 from the commencement of the base they measure only half an inch ; 

 thence they are continued as a narrow fringe for 2 inches more, the 

 entire length of the base of the fin being thus 4 inches, or twice the 

 depth of the anterior part. Only a small part of the caudal is 

 shown : it was evidently powerfully heterocercal. In all these fins, 

 the rays are rather fine for the size of the fish, closely articulated, 

 and exquisitely sculptured externally by oblique ridges and grooves. 

 The marginal fulcra are very small and close. 

 Gonatodus parvidens, n.sp. 

 In my first list of Borough Lee fish remains I indicated an undeter- 

 mined species of this genus as " Gonatodus, sp.," and since that was 

 published an accession of fresh material has convinced me that the 

 species is new. G. parvidens, of which I hope to give a more 

 detailed description afterwards, resembles G. macrolepis, Traq., pretty- 

 closely in its form, scales, and fins, but may be distinguished both 

 from the latter and from G. pundatus, Ag., by the remarkably small 

 size of the maxillary teeth, which, however, still retain the shape 

 characteristic of the genus. 



IV. — The Fallacy of the Theory of the "Permanence of 



Continents." 

 By J. S. Gardner, F.G.S. 



IT is rather remarkable that the Theory of the Permanence 

 of Continents and Oceans has passed so comparatively un- 

 challenged by geologists. I long since attempted to show that 

 Mr. Wallace's supposition that the Cbalk was a shallow and littoral 

 sea deposit was untenable. In comparing analj'^ses of chalk, as he 

 does, with Atlantic ooze, no allowance whatever is made for the loss 

 of iron from the body of tbe chalk by crystallization, nor for the 

 segregation of silica into flints. The Chalk may have undergone so 

 great a change in addition, since its upheaval vast ages ago, through 

 the removal of some of its constituents by percolating water, that com- 

 parative analyses can only be of value when these losses are taken 

 into consideration. The total absence of Globigerina, and almost all 

 the Cretaceous fossils in the decomposed coral mud of Oahu, to which 

 Mr. Wallace would assimilate our chalk, shows that they could not 

 have been deposited under the same conditions ; whilst the dissolution 

 from the chalk of all its mollusca except the few whose shells were 

 j)hosphate of lime, renders any inference drawn from them relatively 

 untrustworthy, seeing that so many of the latter are extinct forms. 



