THE CRETACEOUS SYSTEM 301 



shells of Exogyra imbricata, and others consist largely of 

 Trigonia ventrioosa shells. Parts of the skeleton of a 

 reptile related to Plesiosaurm have been obtained from 

 the cliffs above Picnic Bush. 



A bore-hole (by jumper drill) which is now being 

 sunk near the mouth of the Zwartkops Kiver near 

 sea level, has reached a depth of 3,000 feet, and marine 

 shells, some of which are like those from the Kawson 

 Bridge clay-pit, were obtained at 2,300 feet. The frag- 

 ments are of blue clays and sandy beds. 



In the Sunday's River Valley the marine beds are ex- 

 posed at intervals from near Dunbrody to the mouth of 

 the river. 1 The beds on the Olifant's Kop cliff seem to 

 be the highest in the valley, though from the lack of 

 sufficient exposures it is difficult to ascertain the strati- 

 graphical position of the beds on the left bank near 

 Colchester relatively to those in the more continuous 

 sections above Barkly Bridge. Several fossils certainly 

 occur throughout the marine beds in this valley, though 

 others, especially Trigonia ventrioosa, have been found in 

 the higher beds only. Of some of the most important 

 fossils such as the various species of Holcostephanus only 

 a few individuals have been found, and there are great 

 opportunities for local collectors both in this valley and 

 also in the Coega and Zwartkop Valleys. 



In the outliers of the Uitenhage series to the west of 

 the division of that name deposits similar to the Sun- 

 day's Eiver beds are only known in the Knysna Estuary. 



1 An account of most of the sections is to be found in G. C., x., and a 

 list of accurately determined species from these and other localities in 

 Kitchin's paper in A. S. A. M., vol. vii., pp. 219-24. 





