Marshall. — Fauna of thr Hampdav Beds. 213 



The species are numerous, and their ornamentation distinct and varied, and 

 many of the species appear to have a short range. 



There can now be no doubt that the genus SfrutJiiolarin is derived from 

 Pitgnellus Conrad, or from that modification that has been calk'd CoiicJw- 

 ihijra by McCoy. Conchofhyra parasitica McCoy occurs at the Selwyn 

 Rapids and other places in rocks of Senonian age, and at the Waipara in 

 rocks probably of the same age it is represented by Pugnellvs waiparaensis 

 Trechmann, a closely related species, while at Wangaloa, in rocks that are 

 of very early Tertiary age, Pugnellus australis Marshall occurs, a species 

 quite closely related to P. waiparaensis. At Hampden and Wangaloa there 

 is Struthiolaria minor Marshall, a species that has a callosity extending "ver 

 the greater part of the spire. Pugnellus australis Marshall is thought by 

 Cossmann to be quite probably a Struthiolaria. S. calcar, S. spinosa, and 

 S. tiiberculata have a restricted range in the middle part of the Oamaru 

 system, while S. canaliculata occurs in the portion that is commonly com- 

 pared with the Upper Miocene, and S. frazeri is found in beds that are 

 possibly the equivalent of the Lower Pliocene, and two species extend up 

 to the Recent period. 



Fusinus is another genus that can probably be used in the same way, 

 for F. solidus is found in the Hampden beds, and in other rather higher 

 but still old Tertiary beds. At Wharekuri F. pulcher occurs. F. carinatus 

 occurs in beds that are rather low in the system in Canterbury, whih' 

 F. climacotus is found at Enfield and Target Gully. In the north 

 F. morgani and F. kaiparaensis are also species that appear to liave a 

 restricted range. F. spiralis occurs in Wanganui and Recent beds. 



Exilia is a genus that is said by Cossmann to be characteristic of the 

 Eocene period. In New Zealand E. waihaoensis is found in the Hampden 

 beds and at Waihao, E. dalli extends to the top of the Oamaru limestone, 

 and a third species is found in beds of a low horizon at Enfield. 



Surcula is a genus that is well represented, and many of the s]3ecies 

 have a restricted range. Thus Surcula hamiltoni is found at Hampden, 

 Wharekuri, and Kakahu. Surcula serotina is confined to the beds of low 

 horizon at Hampden and Waihao and at Borton's. Many of the other 

 species have a sufficiently restricted range to allow them to be used as index 

 fossils. 



There are many other genera, such as Pecten, Cardium, V enericardia, 

 Natica, Crassatellites, and Sipho7ialia, that have species which by reason 

 of their common occurrence, distinctness, and short range in time are 

 eminently suitable for indicating the age of certain horizons. 



The relation of various faunas to the Recent fauna and to one another 

 gives another basis for correlation that may be used with the greatest 

 advantage in studying the divisions of the Oamaru system. Thomson 

 compares it with Lyell's original basis for the classification of the European 

 Tertiaries, and says that the great geologist adopted this method because 

 the European fossiliferous Tertiary beds were discontinuous. Surely that is 

 also so in New Zealand, for otherwise we should not still at the present day 

 be worrying about the stratification succession in them after forty years of 

 efiort. The fact that Lyell included the Brachiopoda in his comparisons 

 does not afiect the question. In New Zealand the brachiopods occur so 

 sporadically and in such a small number of species compared with the 

 Mollusca, and the species are so hard to identify with certainty, that they 

 are far less satisfactory for purposes of correlation. Nobody would slavishly 

 follow Lyell to the extent of requiring in New Zealand the same percentages 

 for the different divisions of the Tertiary sediments as those that were 



