1866.] 



60DWIN-AT7STEN BELGIAN TESTIARIES. 



245 



Table III. (continued). 



L. 



Venus rudis, Poli. 



Venus chione, Lin. S. Br. & L., litt, 



40 f. 

 Corbula gibba, Oliv. B.-L., 5-30 f. 

 Cyprina Islandica, B. & Br., 5-80 f. 

 Mya ferruginosa. N. Br., L., 3-80 f. 

 Axinus sinuosus. B.-L., 8-80 f. 

 Lucina borealis. B.-L., litt.-80 f. 

 Pectunculus glycimeris. 10-50-100 f. 

 Modiola marmorata, Forbes. B.-L., 



litt.-40 f. 

 Pecten tigrinus. B.-L., 10-100 f. 



Sowerbyi, 



pusio. Litt. -90 f. 



Anomia ephippium. B.-L., litt.-160f. 



Bulla lignaria, Lin. B.-L., litt.-40 f. 

 eylindracea, Bru^. B.-S.L., litt. 



-90. 



acuminata, Brug. 



conuloidea, Wood. 



utricula, Broc. 



Vaginella depressa. Lusit. latitudes. 

 Spirialis rostralis. ,, 



Pholas papyracea. S. Br., litt.-20 f. 

 Solen ensis, Lin. B.-L., litt. 



strigillatus. L., litt.-lO f. 



Saxicava arctiea. Litt.-160 f. 



rugosa. Br.&L., 6-20f. 



fragilis. 



Syndosmya prismatica. B.-L., 3-100 f. 

 Leda pygmaea, BUI. E. & W. B., L., 



25-50 f. 



It is evident from the foregoing list that the Edeghem fauna is 

 referable generally to a much deeper bed than the Scaldesien. This 

 consideration by itself shuts out such comparisons as have been 

 made ; things so unlike as the assemblages of fossil shells from very 

 different ranges and conditions of sea-bed can only be compared for 

 the purpose of obtaining a knovrledge of vrhat those depths were. 

 Our acquaintance with the distribution of marine species over deep- 

 sea beds is as yet imperfect, but we know that it has its peculiar 

 facies ; and geologists have not sufficiently regarded this, hence much 

 erroneous generalization. It is weU observed by Mr. J. G. Jeffreys*: 

 *' It is obvious that negative evidence of the occurrence of any species 

 (and especially of those which inhabit deep water) in any given area 

 of sea is inadmissible ; and naturalists do not differ from logicians 

 or lawyers in rejecting such evidence." The peculiar forms of the 

 " Crag Noir" could not possibly occur in Scaldesien beds, in respect 

 of their conditions of existence, though they should have been inha- 

 bitants of the same sea at the same time. The occupation of the 

 North Sea area by the true Crag fauna was not of lengthened duration, 

 nor does the fauna itself indicate that change in time which is so 

 clearly to be traced in the accumulations of long periods, whether 

 Palaeozoic, Secondary, or Nummulitic. The Crag is not a formation, 

 but merely a single stage in the Kainozoic series. 



3. Denudation. — The extent to which portions of the rock-forma- 

 tions have been removed, and the character of the surface denuda- 

 tions, are amongst the most interesting of the geological phenomena 

 of Belgium. Such is the denudation which occurred antecedently 

 to the Cretaceous series, and again before the Nummulitic. Por the 

 present I would call attention to that which followed the completion 

 of the Crag-sea beds, because the evidence is very striking, and has 

 a bearing on some views recently put forward by English geo- 

 logists, to the effect that there is evidence of continuity and un- 

 broken marine conditions, from the Suffolk Crag upwards into the 

 Boulder- formation . 



* Ann. and 



Nat. Hist. ser. 2. vol. xvii. p. 168. 



