296 Mr. Weaver on the Structure of the South of Ireland. 



possess a divided dorsal, and three a simple dorsal lobe. Of 

 the 33 species, SO are first made known to us by Professor 

 Phillips ; only three of them having been previously noticed 

 by authors, namely, Goniatites sphcericus (Mart.), Gon. Lis- 

 teri (Mart.), and Go7i. Henslcwi (Sow.) 



I have no doubt, that Professor Phillips, who is so well 

 qualified for the task, will give due attention to this subject 

 in Devon and Cornwall ; and it will be interesting to learn 

 in what degree the Goniatites of the carboniferous limestone 

 in North Devon, near Barnstaple (e. g., at Swimbridge, where 

 they abound), differ from those found in the transition di- 

 stricts of South Devon and Cornwall. The same subject de- 

 serves attention in Ireland*. 



To M. Von Biich we owe the first precise distinction be- 

 tween Nautili and Ammonitesf . The range of the former 

 extends, it is well known, from the oldest to the most recent 

 of the fossiliferous strata, the genus being still in existence. 

 The Ammonites, on the other hand, though equally ancient 

 in origin, do not in their range pass beyond the limits of the 

 cretaceous group. To the same distinguished naturalist we 

 owe the distribution of the Ammonites into 14? families J, the 

 first and oldest of which, the Goniatites, are characteristic of 

 the transition and carboniferous epochs, not extending be- 

 yond the coal formation ; the second, the Ceratites, appear 

 confined to the muschelkalk ; while the remaining 12 fami- 

 lies are distributed through the series of formations extending 

 from the lias to the chalk inclusive. But we are indebted, 

 primarily, namely, in 1828, to Professor Bronn of Heidel- 

 berg, for the important observation so conducive to the di- 

 stinction of formations, that no Ammonites with denticulated 

 lobes have been found in strata of the transition and carboni- 

 ferous aeras, such being confined to the formations of a later 

 origin. This remark was publicly made known by Von 

 Buch in 1829, nearly at the same time that M. Elie de Beau- 

 mont was preparing to announce a similar observation made 

 by himself; and the remark was shortly after confirmed and 

 generalized by Count Miinster§. 



* Count Miinster considers his Goniatites ovatus, found at Gottendorf 

 and Schleitz in the Fichte]gebirge, to be the same as the HJllipsolites {Nau- 

 tilus) ovatns of Sovverbj', which occurs in the Cork band of limestone. 

 And he inquires whether some other species described as Nautili by Mr. 

 Sowerby might not prove to be Goniatites. 



t Annales des Sciences Natui-elles, tome vii. premiere serie, 1829. 



% Annales des Sciences Xaiurelles, tome viii. 1829; and Transactions of 

 the Royal Academy of Sciences of Berlin, April 1, 1830, XJiher die Ammo- 

 niten in den 'dlteren Gebirgs-Schichten. 



§ Von Buch, iibei^ Goniatiten,Decem\iei 15, 1831, in the Transactions of 



