93 REPORT— 1873. 



that an identical set of forms ranged tliroughout. A minutely critical examination 

 has since indicated shades of dift'erence ; yet it may be questioned wliether such 

 are greater than different localities in the same zoological province now present, 

 allowance being made for differences iu the conditions of these old estuarine and 

 lacustrine areas. 



The relations of the land-surface forms of the Wealden fonnations of the 

 European area have been recognized by all naturalists as being Jurassic rather 

 than Cretaceous. In this the Purbeck-AVealden gTOup offers an exact counterpart, 

 zoologically and geologically, of the Permian-Trias group ; just as the marine zoolo- 

 gical relations of the Permian are Palfeozoic, so those of the Purbock are Jurassic ; 

 and when next after each of these, and after the wide spread of purely marine con- 

 ditions over the northern hemisphere at each period, the marine fauna is seen to 

 have undergone a complete change, in the one case Palaeozoic forms go out, and for 

 ever, to be succeeded by Mesozoic or Jurassic; in the other Jurassic forms go out and 

 thje Lower Cretaceous come in, and are those which interchange with the upper- 

 most Wealden fauna at Puufield and the Pays de Bray. 



Did time allow, I might call attention to the results of the labours of the dis- 

 tinguished palpeontologists who have described the forms of life of the Wealden 

 period, both of animals and plants. From them we know that Crocodiles and 

 Chelonians, referable to many genera, abounded in the Wealden waters. These, 

 with the Cycadere of the land, sufhciently mark the temperature of that time as being 

 much liigher than it is here at present. With respect to the numerous large ter- 

 restrial l)inosaurs, it is observable that as yet they are nearly all peculiar to our 

 Wealden lake. The relative level of tliis lalce seems tliroughout to have been 

 such as to have admitted of easy communication and interchange with the waters 

 of the sea ; and this condition may serve to account for some of the peculiarities 

 which its fauna presents. 



On the Temperature and other Physical Conditions of Inland Seas, in their 

 relation to Geologiad Inquiry. By Williaji B. Carpenter, M.D., LL.D., 

 F.11.S. 



After givin» a brief account of the Temperature-phenomena of the Deep Sea, as 

 made known hy recent observations (see Proceedings of Section A, p. 48), Dr. Car- 

 penter contrasted these with the Temperature-phenomena of the Mediterranean 

 and other inland seas. In the Western basin of the Mediterranean, the temperature 

 of the surface varies with the season, from about 54° F. in winter to 76° or even 80° 

 in summer. But the superheating influence of solar radiation does not extend 

 much below 50 fathoms, and ceases to manifest itself at 100 fathoms ; and from 

 this depth to the bottom, which in some parts lies at a depth of ICOO fathoms, 

 there is a uniform temperature of 54°. From the coincidence of this imiform tem- 

 perature with that which seems to be the constant mean of the earth's crust in the 

 Mediterranean area, — as indicated by that of the deep tanks in Malta, and of a cave 

 in Pantellaria, — the Author had thought, in the first instance, that it might be de- 

 pendent upon 6;((6jacent warmth. But subsequent inquiries have satisfied him that 

 it is mainly determined by the average «vV(<e;--tomperature of the area. As he 

 pointed out last year (Proceedings, p. 51), the marked contrast between the tem- 

 perature of the deep stratum of the Mediterranean and that of the outside Atlantic, 

 obviously shows that depth jjer 8e has no eft'ect in reducing Oceanic temperature, 

 and that the coldness of the Sea-bottom in the Atlantic must depend on a flow of 

 glacial water from the Polar area. He ice it may be concluded that if the Strait 

 of Gibraltar were deep enough to admit the cold stratum, the temperature of the 

 deeper portion of the Mediterranean would be considerably lower than it is. But 

 as the " ridge " between Capes Trafalgar and Spartel is shallow enough to prevent 

 the entrance of any but the surface-stratum of Atlantic water, the winter-tempera- 

 ture of which is as high as that of the Mediterranean, the latter cannot be chilled 

 hy it ; and the constant temperature of the whole mass of its water from 100 fathoms 

 downwards may be regarded as its isocheimal, — the solar heat to which its surface 



