CLIMATIC ZONES 79 



sions have been widely accepted in some quarters, and combated in 

 others. 

 I Neumayr's Climatic Zones of the Jurassic. These from the 

 north southward are as follows : 



1. Boreal Zone. Characterized by the presence of the ammonite 

 genera, Cardioceras, Oxynoticeras, and Virgatitcs, the belemnite 

 Cylindroteuthis, and the pelecypod Ancella; also by the absence of 

 reef-building corals, and of the ammonite genera : Phylloceras, 

 Lytoccras, Simoceras, and Lissoceras, and the scarcity of the 

 genera : Oppelia, Hecticoceras, Peltoccras, and Aspidoecras. The 

 boundary between this and the next zone was placed at latitude 45° 

 in the Pacific, but further north in the Atlantic and Europe. 



2. North Temperate Zone. This comprised especially the prov- 

 inces of Central Europe, and was characterized by the rarity of the 

 ammonite genera which attained their maximum in the two adjoin- 

 ing zones ; and also by the appearance of reef corals, and the 

 predominance of the ammonite genera : Oppelia, Reineckia, Pel- 

 toceras, and Aspidoceras. The boundary between this and the next 

 zone was placed at latitude 32° N. in the Pacific, but oscillated about 

 latitude 40° N. in the Atlantic and in Eurasia. 



3. Equatorial Zone. This comprised in Europe the Mediter- 

 ranean province and was characterized by the abundance of the am- 

 monite genera Phylloceras, Lytoccras, and Simoceras, the belem- 

 nites Belemnopsis and Duvalia, and the brachiopod. Pvgope. The 

 boundary between this and the next zone was placed at about lati- 

 tude 32° S. 



4. South Temperate Zone. This reproduced the characters of 

 the north temperate zone. 



Discussion of the Subject of Climatic Zones. 



Of the zones mentioned above, the colder or boreal zone appears 

 to be well established, but the differentiation of the warmer belt 

 into three distinct zones is less generally supported by the evidence. 

 In Europe the north temperate province of Neumayr represents, 

 according to Haug (42), the shallow water zone of the warm belt, 

 while the equatorial zone corresponds in general with the open and 

 deep Thetys sea. The distribution of the genera in these provinces 

 is due more to this difference in depth and the corresponding differ- 

 ence in temperature than to zonal distinctness. That annual 

 changes of temperature existed in Jurassic time is shown by the de- 

 velopment of annual growth rings in the stems of Abietinese of 

 that period found on King Charles Land. (78° N. lat.) (Gotan- 



