54 Annals of the South African Museum. 



lead us to a somewhat different conclusion concerning the relation of 

 the equatorial and the southern ocean at that period. In order 

 to form an approximately correct picture, we must at least compare 

 faunas of similar age, for it is probable that migration from one area 

 into another may take place exceedingly rapidly when measured 

 by geological standards, and that a fauna may thus become quickly 

 modified as regards some of its most salient characteristics. 

 Dr. Kossmat has brought forward evidence to show that in the 

 migration of Upper Cretaceous cephalopods " the distribution of 

 the species did not require any geologically measurable time." * 

 In contrasting the Uitenhage fauna with any occurrences on the 

 western shore of his equatorial sea, Neumayr was not able to 

 compare with contemporaneous faunas, except perhaps that of the 

 Belemnite-beds in the north-west of Madagascar. But in this case 

 the possible grounds of comparison were of the most slender 

 description, since in the Neocomian of Madagascar the known fauna 

 consisted solely of belemnites ; and hence the very hazardous nature 

 of the generalisations which Neumayr was led to make as a result of 

 the comparison. It is very probable that the great contrast between 

 these faunas may owe its strength in no slight measure to differences 

 of local facies, a factor which does not seem to have been sufficiently 

 taken into account ; f the Belemnite-beds of Madagascar probably 

 represent deeper water .conditions, in contrast to the littoral character 

 exhibited by the Uitenhage molluscs. Moreover, it is easy to 

 conceive that the lines of communication between the two areas 

 were in reality somewhat indirect, without necessarily accepting 

 Neumayr's extreme interpretation of the facts. It may be admitted 

 that the arguments drawn from evidence furnished by distribution at 

 an earlier and a considerably later age decidedly favour the view 

 that in Neocomian times a ridge extended from India to South 

 Africa ; this, however, may have been only partially elevated into 

 land, and one or more intervening tracts of shallow water would suffice 

 to allow passage from north to south. Pavlow J and Uhlig have 

 pointed out the very close affinity between species of Holcosteplianus 

 from the Uitenhage beds and H. schenki (Opp.) from the Spiti 

 Shales, while Kossmat has also remarked on the close relationship 

 between Uitenhage fossils and Lower Neocomian forms in the Salt 



* Kossmat (3), pp. 78-81. 



f Since these sentences were written (in 1903), Lemoine has expressed the same 

 opinion ; see Lemoine (1), p. 391. 



I Pavlow and Lamplugh (1), p. 493 (p. 135 of authors' separate copy). 

 Uhlig (4), p. 132. 



