ANISTVERSAET ADDRESS. xlix 



circumstances of the case, we possess more abundant positive evidence 

 regarding Fishes and marine lloUusks than respecting any other forms 

 of animal life ; and yet these offer us, through the whole range of 

 geological time, no species ordinally distinct from those now living ; 

 while the far less numerous class of Echinoderms presents three, 

 and the Cnistacea two such orders, though none of these come down 

 later than the Palaeozoic age. Lastly, the Eeptilia present the ex- 

 traordinary and exceptional phenomenon of as many extinct as 

 existing orders, if not more ; the four mentioned maintaining theii' 

 existence from the Lias to the Chalk inclusive. 



Some years ago one of yom- Secretaries pointed out another kind 

 of positive pal?eontological evidence tending towards the same con- 

 clusion — afforded by the existence of what he termed " persistent 

 types " of vegetable and of animal life*. He stated, on the authority 

 of Dr. Hooker, that there are Carboniferous plants which appear to 

 be generically identical with some now living ; that the cone of the 

 Oolitic Araucaria is hardly distinguishable from that of an existing 

 species ; that a true Piiim appears in the Pui'becks and a Juglans 

 in the Chalk: while, from the Bagshot Sands, a BcmJcsia whose 

 wood is not distinguishable from that of species now living in Aus- 

 traha had been obtained. 



Turning to the animal kingdom, he affirmed the tabulate corals 

 of the Silurian rocks to be wonderfully like those which now exist ; 

 while even the famihes of the Aporosa were all represented in the 

 older Mesozoic rocks. 



Among the MoUusca similar facts were adduced. Let it be borne 

 in mind that Avicida, Myt'dus, Chiton, Natica, Patella, Trochus, 

 Biscina, Orhicida, Lingida, Rhynclionella, and Naiddus, all of which 

 are existing genera, are given without a doubt as Silurian in the 

 last edition of 'Siluria'; while the highest forms of the highest 

 Cephalopods are represented in the Lias by a genus, Belemnoteuthis, 

 which presents the closest relation to the existing Loligo. 



The two highest groups of the Annulosa, Insecta and Arachnida, 

 are represented in the Coal either by existing genera or by forms 

 differing from existing genera in quite minor peculiarities. 



Turning to the Yertebrata, the only palseozoic Elasmobranch Eish 

 of which we have any complete knowledge is the Devonian and Car- 

 boniferous Pleuracanthus, which differs no more from existing Sharks 

 than these do from one another. 



Again, vast as is the number of undoubtedly Ganoid fossil Eishes, 

 and great as is their range in time, a large mass of evidence has re- 

 cently been adduced to show that almost all those respecting which 

 we possess sufficient information are referable to the same subordinal 

 groups as the existing Lepidosteus, Pohjpierus, and Sturgeon ; and 

 that a singular relation obtains between the older and the younger 

 Eishes ; the former, the Devonian Ganoids, being almost all members 



* See the abstract of a Lecture " On the Persistent Types of Animal Life," 

 in the ' Notices of tlie Meetings of the Royal Institution of Great Britain,' June 3, 

 1859, vol. iii. p. 151. 



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