Revieics — Barrande's Cephalopoda. 39 



nearly one-half of the known species from the ancient rocks of 

 the two continents. The specimens are said to occur ver}'^ abundantly, 

 and in a good state of preservation, often affording evidence of the 

 internal structure. After a critical analysis of the distribution of the 

 order in time, and a rigid investigation of the origin and growth of 

 the shell in the NautUidce, M. Barrande feels a positive conviction 

 that no facts favourable to the theory of Evolution, or descent by 

 modification, can possibly be derived from a systematic study of the 

 Cephalopoda. 



In a review of the Embryological literature of the subject, it is 

 mentioned that Dr. Eobert Hooke was the first to call attention (in 

 a paper read before the Koyal Society of London in 1696), to the 

 initial development of the shell in Nautilus, and the value of the 

 publications of Prof. Phillips, MM. de Koninck, Franz Hauer, 

 Alph. Hyatt, F. and G. Sandberger, etc., etc., in the present century, 

 is duly acknowledged. It appears from their researches, and those 

 of M. Barrande, that there exists a most important radical difference 

 between the early stages of the development of the families Ammon- 

 itidcB and Goniatidcs, as compared with that of the Nautilidce, an 

 ovisac being always present in the former, and absent in the latter. 

 This fact aione is considered by M. Barrande as sufficient evidence 

 of the non-derivation of the Ammonites, and Goniatites from the primi- 

 tive Nautilidce, for, it is urged, if a correspondence in the embryonic 

 characters of diverse genera be regarded as proof of their descent by 

 modification from some common ancestor, it must necessarily follow 

 that so marked a contrast is a sure indication of an independent 

 origin. Again, it is contended that the embryonic type of the 

 primitive JVautilidce persists unchanged up to the present time, while 

 that of the families Goniatidcs, and AmmonitidcB, appears suddenlv, and 

 retains its distinctive characters until the final extinction of all the 

 genera of which they are composed. Moreover, an examination both 

 of the external and internal structure of the Cephalopods, whether 

 as considered with regard to the position and diameter of the syphon, 

 or the size, curvature, ornamentation, and composition of the shell, 

 absolutely fails to furnish any evidence of progressive development, 

 but shows, on the contrary, that any variation in these characters 

 had no effect whatever, either upon the number of a species, or the 

 vertical range of a genus. For instance, M. Barrande observes that 

 although the Nautilidce possessed of a compound opening might be 

 looked upon as more highly organized than those with a simple one, 

 yet both these forms were simultaneously represented in the lowest 

 beds of the second Silurian zone, the simpler forms also were speci- 

 fically far more numerous, and endowed with a much greater power 

 of vitality. Thus, as the accompanying Table shows, five out of the 

 six compound types were restricted to the Silurian rocks, one only 

 ranged up to the Carboniferous, while, of the 12 simpler forms, but 

 six died out at the close of the Silurian, the straight-shelled Ortlio- 

 ceras living on to the Trias, and the whorled Nautilus persisting even 

 to the recent period. The evidence of the few admitted intermediary 

 forms is also regarded as invalid, on account of the anachronism in- 



