1863.] 



FERGTJSSON" DELTA. OP THE GANGES. 



321 



P.S. 27th June, 1863. — Since the foregoing communication was 

 made to the Geological Society, I have received a copy of Dr. A. 

 Oppel's ' Palaeontologische Mittheilungen,' Stuttgart, 1862. 



The first part of this most valuable work is devoted to a descrip- 

 tion of Macrurous Crustaceans of the Jurassic formations of Ger- 

 many, &c, and is illustrated by 38 excellent plates. The author 

 has, I observe, adopted Germar's generic name of Mecocheirus in his 

 descriptions of the Solenhofen Crustacea. 



Although Dr. Oppel has added more than 50 new species to the 

 list of Jurassic Crustacea, none of them agree, even generically, with 

 that just described from the Lias of Lyme Regis. — H. "W. 



EXPLANATION OF PLATE XI. 



Scapheus ancylochelis, H. Woodw., four-fifths the natural size. 



Apeil 1, 1863. 



S. N". Carvalho, Jun., Esq., 6 Aberdeen Park, Highbury Grove, N., 

 and William Edwards Wood, Esq., Tamworth Castle, Tamworth, 

 were elected Fellows. 



The Rev. Dr. 0. Heer, Professor of Botany in the University of 

 Zurich ; Sign. P. Savi, Professor of Geology in the University of 

 Pisa ; Sign. G. Ponzi, Professor of Comparative Anatomy and Phy- 

 siology in the University of Home ; Dr. J. Leidy, Professer of Ana- 

 tomy in the University of Pennsylvannia ; II Marchese Pareto, of 

 Genoa ; and Professor A. Daubree, of the Jardin des Plantes, Paris, 

 were elected Foreign Correspondents. 



The following communication was read : — 



On Recent Changes in the Delta of the Ganges. 

 By James Feegusson, Esq., F.R.S. 



[Communicated by the President.] 



[Plate XII.] 



Contents. 



I. 



II 



of 



are 



General Considerations. 



1. Introduction. 



2. Oscillation of Rivers. 



3. Elevation of the Banks 



Rivers. 



4. Secular Elevation of Deltas. 



5. Mode in which Deltas 



elevated. 

 Physical changes in the Yalley of 



the Granges. 

 Upheaval of the Madoopore 



Jungle. 

 Silting-up of the Sylhet Jheels. 

 Eastern Gap in the seaward 



face of the Delta. 

 Change in the bed of the 



Brahmapootra. 



5. Opening of the R. Jennai. 



6. Jessore group of rivers. 



7. Natore group of rivers. 



8. Kishnaghur group of rivers. 



9. Changes in the course of the 



R. Teesta. 

 10. Retrocession of the junctions 



of tributary streams with 



main rivers. 

 III. Historical evidence of the changes 



in the Delta of the Ganges. 

 TV. Increase of the Delta seaward. 



1. Silt held in suspension in 



Ganges waters. 



2. Swatch of " No Ground." 

 V. Appendix. 



