x.] PERSISTENT TYPES OF LIFE. 189 



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 Crustacea two, such orders, 

 though none of these come down later than the Palseozoic age. 

 Lastly, the Reptilia present the extraordinary and exceptional 

 phenomenon of as many extinct as existing orders, if not more ; 

 the four mentioned maintaining their existence from the Lias to 

 the Chalk inclusive. 



Some years ago one of your Secretaries pointed out another 

 kind of positive palaeontological evidence tending towards the 

 same conclusion afforded by the existence of what he termed 

 &quot; persistent types &quot; of vegetable and of animal life. 1 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 dis 

 tinguishable from that of an existing species ; that a true Pinus 

 appears in the Purbecks, and a Juglans in the Chalk ; while, 

 from the Bagshot Sands, a Banksia, the wood of which is not 

 distinguishable from that of species now living in Australia, 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 families of the Aporosa were all 

 represented in the older Mesozoic rocks. 



Among the Molluska similar facts were adduced. Let it be 

 borne in mind that Avicula, Mytails, Chiton, Natica, Patella, 

 Trochus, Discina, Orbicula, Lingula, Rhynchonella, and Nautilus, 

 all of which are existing genera, are given without a doubt as 

 Silurian in the last edition of &quot; Siluria ; &quot; 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. 



1 See the abstract of a Lecture &quot;On the Persistent Types of Animal 

 Life,&quot; in the &quot; Notices of the Meetings of the Koyal Institution of Great 

 Britain.&quot; June 3, 1859, vol. iii. p. 151. 



