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which that learned traveller, in his " Essay on the Superposition of 

 Rocks," considered to belong to the Jura Formation. Von Buch takes 

 a different view, and places them higher up in the series ; that is, in the 

 Chalk Formation. After a careful perusal of Von Buch's work, and 

 a re-examination of the specimens, Mr. Lea still holds to his previous 

 opinion, that these forms belong properly to the Oolitic series, and 

 not to the Chalk. He is the more confirmed in this opinion from 

 having since been enabled to examine Captain Grant's Memoir on 

 the Geology of Cutch, recently published in the Geological Society's 

 Transactions of London, Second Series, Vol. V. Part 2 ; where the 

 forms represented have a strong alliance to those described by Mr. 

 Lea. Captain Grant states, that the miner alogical character of the 

 rock " greatly resembles the English Lias ; but its fossils have been 

 found, after a careful examination by Mr. James Sowerby, to assimi- 

 late very closely to those of the Oolitic beds," &c. 



Mr. Lea's paper contains descriptions of the following species : — 



Orthocera Humboldtiana. Testa recta, elongato-conica, subcylin- 

 dracea; articulis transversis, subdistantibus. 



Ammonites Tocaimaensis. Testa orbiculari; anfractibus planula- 

 tis, transversim costulatis ; costis planulatis ; periphasria minute sul- 

 cata. 



Ammonites Occidentalis. Testa orbiculari, utrinque umbilicata; 

 anfractibus rotundatis, transversim costulatis; periphasria rotunda, 

 sulco circulari destituta. 



Ammonites Gibboniana. Testa orbiculari; anfractibus compres- 

 sis; costis elevatis, carinatis, remotiusculis ad periphaeriam. 



Ammonites Vanuxemensis. Testa orbiculari, utrinque umbili- 

 cata; anfractibus convexo-cylindraceis, transversim crebrissimeque 

 costulatis; periphasria rotunda, sulco circulari destituta. 



Ammonites Americana. Testa orbiculari; anfractibus subplanis, 

 oblique costulatis; periphasria sulcata. 



Trigonia Gibboniana. Testa ovato-trigona, multicostata; costis 

 transversis, subtuberculato-asperis ; area postica carinata. 



Trigonia Tocaimana. Testa trigona, postice producta inflata; 

 costis transversis laevibus. 



Trigonia Hondaana. Testa ovato-trigona, inflata, multicostata; 

 costis transversis, tuberculato-nodosis ; area postica elevata, crebris- 

 simeque nodosa. 



Natica Gibboniana. Testa ovata, ventricosa; spira productius- 

 cula ; anfractibus quinis, subplanulatis ; apertura contracts., elongata. 



