290 THE ORIGIN OF SPECIES 



Mzard-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 inhabitants 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 

 Cirripedes, I stated that, from the large number of existing and 

 extinct 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 fifty fathoms; from the perfect manner 

 in which specimens are preserved in the oldest tertiary beds; 

 from the ease with which even a fragment of a valve can be rec- 

 ognized; from all these circumstances, I inferred that, had sessile 

 cirripedes existed during the secondary periods, they would cer- 

 tainly have been preserved and discovered; and as not one species 

 had then been discovered in beds of this age, I concluded that 

 this great group had been suddenly developed at the commence- 

 ment 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 unmistakable 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 Chtham- 

 alus, 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 have abundant evidence of the exist- 

 ence of this group of animals during the secondary period. 



The case most frequently insisted on by palaeontologists, of the 

 apparently sudden appearance of a whole group of species, is that 

 of the teleostean fishes, low down, according to Agassiz, in the 

 Chalk period. This group includes the large majority of existing 

 species. But certain Jurassic and Triassic forms are now commonly 

 admitted to be teleostean; and even some palaeozoic forms have 

 thus been classed by one high authority. If the teleosteans had 

 really appeared suddenly in the northern hemisphere at the com- 

 mencement of the chalk formation, the fact would have been 

 highly remarkable; but it would not have formed an insuperable 

 difficulty, unless it could likewise have been shown that at the same 



