284 SUDDEN APPEARANCE OF [Chap. X 



any tertiary stratum ; but now extinct species have been discovered 

 in India, South America, and in Europe, as far back as the miocene 

 stage. Had it not been for the rare accident of the preservation of 

 footsteps in the new red sandstone of the United States, who would 

 have ventured to suppose that no less than at least thirty different 

 bird-like animals, some of gigantic size, existed during that period ? 

 Not a fragment of bone has been discovered in these beds. Not long 

 ag?, pakeontologists maintained that the whole class of birds came 

 suddenly into existence during the eocene period ; but now we 

 know, on the authority of Professor Owen, that a bird certainly 

 lived during the deposition of the upper greensand ; and still more 

 recently, that strange bird, the Archeopteryx, with a long lizard- 

 like tail, bearing a pair of feathers on each joint, and with its wings 

 furnished with two free claws, has been discovered in the oolitic 

 slates of Solenhofen. Hardly any recent discovery shows more 

 forcibly than this, how little we as yet know of the former inhabi 

 tants of the world. 



I may give another instance, which, from having passed under 

 my own eyes, has much struck me. In a memoir on Fossil Sessile 

 Cirri pedes, I stated that, from the large number of existing and 

 oxtinct tertiary species ; from the extraordinary abundance of the 

 individuals of many species all over the world, from the Arctic 

 regions to the equator, inhabiting various zones of depths from the 

 upper tidal limits to 50 fathoms ; from the perfect manner in which 

 specimens are preserved in the oldest tertiary beds ; from the case 

 with which even a fragment of a valve can be recognised ; from all 

 these circumstances, I inferred that, had sessile cirripedes existed 

 during the secondary periods, they would certainly have been pre- 

 served and discovered ; and as not one species had then been dis- 

 covered in beds of this age, I concluded that this great group had 

 been suddenly developed at the commencement of the tertiary series. 

 This was a sore trouble to me, adding as I then thought one more 

 instance of the abrupt appearance of a great group of species. But 

 my work had hardly been published, when a skilful palaeontologist, 

 M. Bosquet, sent me a drawing of a perfect specimen of an unmis- 

 takeable sessile cirripede, which he had himself extracted from the 

 chalk of Belgium. And, as if to make the case as striking as 

 possible, this cirripede was a Chthamalus, a very common, large, 

 and ubiquitous genus, of which not one species has as yet been 

 found even in any tertiary stratum. Still more recently, a Pyrgoma, 

 a member of a distinct sub-family of sessile cirripedes, has been 

 discovered by Mr. Woodward in the upper chalk ; so that we now 



