362 Revieios — Barrande's Cephalopoda of Bohemia. 



family of the NautilidcB, very varied in form, from Orthoceras to 

 Nautilus and TrocJioceras, as proved by the second faunae of the 

 N. American and N. European areas. In Bohemia, the second 

 fauna only offers straight forms of the family, and the " colonies " 

 even have only given two curved forms of the genus Cyrtoceras. 



The great development of the Nautilidcs in Bohemia occurs in 

 Barrande's etage E, in which, more than 637 specific forms of the 

 family occur (or including the supplementary lists of Barrande's 

 Serie tardive, no less than 856 species). No species occur in the 

 beds above belonging to the zones fl,f2,gl,g2,h\it after this 

 long interval Nautilus reappears in zone g 3, with three new species 

 different from those of zone E. Meanwhile the genus Goniatites is 

 absolutely unknown in the second fauna of all Silurian countries in 

 either continent which have been examined up to date.^ The 

 earliest appearance of Goniatites in Bohemia was during the 

 deposition of Barrande's zone /2, in which he shows the existence 

 of seven species of that type. 



Now it is interesting to notice that this epoch of the first appear- 

 ance of Goniatites corresponds to the cessation, which has been just 

 noticed, in the existence of Nautilus in Bohemia. But, Barrande 

 remarks, this fact does not tend to prove the filiation of the new 

 type to the more ancient, because, in reality, where the new form, the 

 first Goniatites, appeared suddenly in the Bohemian basin, there 

 was not a single Nautilus to give birth to them. Further, at its 

 first appearance in zone / 2, the genus Goniatites furnishes 7 distinct 

 species, while the genus Nautilus only furnished 5 during its 

 temporary existence in Bohemia in zone e 2 : numbers which are 

 far from corresponding with the slow and successive steps in trans- 

 formation, admitted by theory. In fact, all the appearances and 

 disappearances have taken place suddenly. 



Some time after its first appearance, Goniatites seems to disappear 

 during the deposition of the very thick zone g 1, at the top of which 

 we again find it. It then continues with variations in the number 

 of its specific representatives through the zones g 2,g 3, hi, attaining 

 its maximum number (14) in g 3. Now it is precisely during the 

 deposition of this same zone that we find Nautilus reappearing with 

 three species. It is difficult to imagine how it reproduces itself after 

 so long a cessation, precisely at the time of the maximum im- 

 portance of the Goniatites, which theory would indicate as replacing 

 the Nautili. 



Barrande here gives an amusing (p. 75) imaginary discourse of 

 an evolutionist lecturer on the derivation of the Goniatite from the 

 Nautilus, " which it replaces at its disappearance from the seas of 

 Bohemia without our exactly knowing why," " mais sans doute par 

 I'effet de la selection naturelle " — and discusses the total discord- 

 ance which is here proven between theory and fact, with reference 



^ The question of the asserted occurrence of two forms of Bactrites, one in 

 Bohemia, one in Russia, in the second fauna, will be found fully discussed in vol. iii. 

 of Texte, p. 804. 



