GEOLOGY. 318* 



Whether the relative size of related species indicates a 'degree of difference is 

 yet undetermined. 



The Jurassic fossils extend the same approximate uniformity onward to 

 the Jurassic period, or prove a recurrence of it, if it had been interrupted. 



Capt. M'Clintock, in the narrative of his expedition, thus speaks of the 

 fossils of Prince Patrick's Land. " The fossils are all small, and of only a 

 few varieties, some being Ammonites, but the greater part bivalves." "I 

 picked up also what appeared to be a fossil bone (Ichthyosaurus ?) only part of 

 it appearing out of the fragment of the rock." The sujiposed Ichthyosaurian 

 bone was afterwards lost. Jurassic fossils have also been found at Katmai 

 Bay, or Cook's Inlet, in northwest America (60 K, 151 W.)j and Dr. 

 Grewingk mentions the species of Ammonites Wosnessenski, A, bi}jlex ? (the A. 

 biplex of Mayen from Jurassic deposits in the Andes, in latitude 34, south of 

 Valparaiso, is stated to be not distinguishable from this), Belemnites paxittosus, 

 and Vnio Liassinus. Professor Haughton of Dublin, in an addenda to Capt. 

 M'Clintock's narative, remarks upon these interesting discoveries as follows : 

 The discovery of such fossils in situ in 7G north latitude, is calculated to 

 throw considerable doubt upon the theories of climate which would account 

 for all past changes of tempcratui-e by changes in the relative position of land 

 and water on the earth's surface. No attempt, that I am aware of, has ever 

 been made to calculate the number of degrees of change possible, in conse- 

 quence of changes of position of land and water; and from some incomplete 

 calculations, I have myself made on the subject, I think it highly improbable 

 that such causes could have ever produced a temperature in the sea at 70 

 north latitude which would allow of the existence of Ammonites, especially 

 Ammonites so like those that lived at the same time in the tropical warm seas 

 of the south of England and France, at the close of the Liassic and the com- 

 mencement of the lower Oolitic period." Abridged from Sittiman's Journal. 



ON THE IiABITABILITY OF THE MOON. 



Sir John Herschel, in the last edition of his "Outlines of Astronomy,'"-' 

 1858, has added the following paragraph on the " habitability of the moon :" 



" On the subject of the moon's habitability, the complete absence of air, 

 if general over her whole surface, would of course be decisive. Some consid- 

 erations of a contrary nature, however, suggest themselves in consequence 

 of a remark lately made by Prof. Hansen, viz., that the fact of the moon 

 turning always the same face towards the earth is in all probability the result 

 of an elongation of its figure in the direction of a line joining the centres of 

 both the bodies acting conjointly with a noncoincidence of its centre of gravity 

 with its centre of symmetry. To the middle of the length of a stick, loaded 

 with a heavy weight at one end and a light one at the other, attach a string, 

 and swing it round. The heavy weight will assume and maintain a position 

 in the circulation of the joint mass further from the hand than the lighter. 

 This is not improbably what takes place in the moon, and the reader may 

 consider the moon as retained in her orbit about the earth bv some coercino- 



" 



power analogous to that which the hand exerts on the compound mass above 

 described through the string. Suppose, then, its globe made up of materials 

 not homogeneous, and so disposed in its interior that some considerable pre- 

 ponderance of weight should exist excentrically situated: then it will be 

 easily apprehended that the portion of its surface nearer to that heavier por- 

 tion of its solid contents, under all the circumstances of a rotation so adjusted, 



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