24:6 Transactions. 



the actual faunal relationships between the different strata in a distinct 

 manner when the collections which have been made in the different 

 localities vary much in the number of species. For instance, when a com- 

 parison is made between the Otiake and the Target Gully faunas one is 

 comparing a collection of 61 species with one of 212 species. One would 

 naturally expect that a high percentage of the former would be found in 

 the latter. On the other hand, only 28 per cent, of the Target Gully 

 species could occur in the Otiake collection. On the whole, it appears to 

 be the best plan to take each collection separately and calculate what 

 percentage of the species that occur in each of the other localities is found 

 among the species that occur in the stratum which is being considered. 

 A comparison is also made with the fauna of the Recent beds and of the 

 fauna that has been recorded from the Wanganui beds. In the latter some 

 200 species are recorded by Hutton, but the collection that he describes 

 has been made from a large number of horizons, though all of them are 

 younger than the strata at Oamaru and younger than those of the 

 Trelissick Basin. It appears to me 2:)robable that no single horizon at 

 Wanganui will yield more than 150 species of fossil MoUusca, even when 

 fuUy collected. Of the Recent MoUusca it seems that no more than 400 

 of the recorded species could be expected to occur under the conditions 

 of depth of water in which the Oamaru deposits were laid down. This, 

 at any rate, is the assumption that is made, and in all of the percentage 

 calculations it is assumed that the Recent fauna consists of 400 species only. 

 The various beds from which collections have been made may be 

 described as follows : — 



(1.) Hampden : On the coast about three miles north of the township 



of Hampden, or about fifteen miles south of Oamaru. The 



beds are unctuous green marls with a good deal of glauconite. 



Perhaps some 1,000 ft. above the base of the Oamaru system 



in that locality. 

 (2.) Wharekuri : Typical glauconite sands. Exposed on the left bank 



of the Waitaki River six miles from Kurow, about thirty miles 



north-west of Oamaru. 

 (3.) Otiake : Close to the right bank of the Waitaki River, four miles 



south-east of Kurow, or twenty-five miles north-west of Oamaru. 



The rocks are gritty polyzoan limestones which are higher in 



the series than the Wharekuri beds and probably rest directly 



on them. It is very generally admitted that this is the horizon 



of the Oamaru or Ototara limestone. 

 (4.) Target Gully : These are about half a mile from the Oamaru 



Railway-station, close to the Eden Street bridge. The beds are 



greyish sands with a little glauconite. The beds rest some 30 ft. 



above the Oamaru or Ototara limestone. 

 (5.) Awamoa : Near the coast about four miles south of Oamaru. The 



beds are a blue mudstone, which is admitted to be a higher 



* horizon than the Target Gully beds. 



In addition some comparisons are made with the Bortonian beds of 



Park* and also with the fauna of two beds in the Trelissick Basin, which 



have lately been fully listed by Speight,! and with the Pakaurangi fauna 



of North Auckland. 



* J, Park, N.Z. Geol. Surv. Bull. No. 20, p. 34, 1918. 



t R. Speight, Trans. X.Z. InM., vol. 49, pp. .346, 348, 1917. 



