Rev. A. Irving — On the Permian and Trias. 



317 



the individuals being rare, insignificant, and small. Cephalopods are 

 fast decreasing, two forms only occur in the Zechstein, and a very- 

 few more in Eussia and America. Trilobites have quite disappeared, 

 and are replaced by a Cypridean form and a Limulus (?). Fishes are 

 mostly heterocercal small-scaled ganoids, the abundance of individuals 

 being enormous. The prevalent forms of the cold-blooded Vertebrata 

 have taken a new type since the Carboniferous period, but Thecodont 

 Amphibians have vertebrae still biconcave (as in fishes) and teeth 

 set like those of the Crocodile. The development of Keptiles has 

 made an important advance by the appearance of a higher type. 



The German Trias is poor in Cephalopods : Nautilus hidorsatus is 

 the chief representative of the Nautilidse, while the Ammonitidee 

 have gained a footing in the form Ceratites. Quite otherwise and 

 manifold is the character of the Cephalopoda of the Alpine Trias, 

 the peculiarity of which consists in the assemblage found there of 

 Palaeozoic and Mesozoic types. Fishes of the Trias are partly 

 heterocercal, small-scaled ganoids, though the non-symmetry of the 

 tail is less marked than in ganoid forms of the earlier periods ; the 

 ossification of the vertebral column has also greatly progressed. 

 True osseous fishes do not as yet exist. In some localities ganoid 

 scales are so common in the upper strata of the German Bunter that 

 some layers of the sandstone are coloured almost black by them. 

 Eemains of the oldest known mammal belong to the final stage of 

 the Trias. In this period certain Crinoids (with the widely-distri- 

 buted and highly characteristic Encrinus liliiformis, Lam.), Bivalves, 

 Cephalopods, Reptiles, and Fishes play a prominent part. 



Comparative Table of the Organic Remains of the Dyas and Trias 

 of Germany (after Credner). 



DYAS. 



FLORA. 

 Caulerpites* (fucoid) 



Calamites gigas* \ 



Annularia > Equisetace/E. 



Asterophyllites ) 



^ 



Neuropteris 



Sphenopteris 



A lethopteris 



Odontopteris j> FiLlCES i Sagenopieris {S) 



TRIAS. 



/ Equisetiim arenacewn* (B K). 

 \ E. columnare (K). 

 \ E. Lehmati7iianum (K). 

 I Schizoneura paj'adoxa (B). 



{ Anoinopteris, with A. Moitgeoti^E K). 

 Clatkopteris, with C. Munsteriaiia[K.). 

 Gut bier a (B). 



Cyatheites 



Psaronarms* 



i(^ubicaulis* 



Noggerathia 



tree- 

 ferns" 



Caidopteris Vollzi (B). 

 I Taiiioptcris, with T. vittata (K). 

 \_Pecopteris, with P. Stiittgartiensis (K). 



[ Pterophyllum yUgeri (K). 

 Pt. longifoliu7n (K). 



P J ^^- Braziniamtni (K). 

 I Zamites (K). ^ 



new types. 



Walchia ... 

 Ullmannia 



Otozamites (K). 

 \_Pterozamites (K) 

 ( Albertia elliptica (B). 

 I Volizia heterophylla (B K). 

 ■{ Pallisya (K) \ 

 I Thuites (K) > new genera. 

 \^PalcEoxyris (K) ) 

 Lepidodendron is rare, Sigillaria and Stigmaria almost extinct in the Dyas. 



Conifers 



