8 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [NoV. 20, 



4. On a Volcanic Phenomenon witnessed in Manilla. 

 By John G. Yeitch, Esq. 

 [Extract of a Letter* to Dr. J. D. Hooker, F.R.S., F.G.S.] 

 On the 1st iilt. a portion of the Eiver Pasig, on the banks of which 

 the city of Manilla is situated, presented an extraordinary appearance, 

 which continued with but slight interruption from 6 to 10 a.m. The 

 oldest inhabitant never remembers having seen or heard of a similar 

 phenomenon. 



The river, for the space of a quarter of a mile from east to west, 

 and having at this point a depth of 15 to 18 feet, appeared in a state 

 of violent fermentation, as if some commotion were taking place in 

 parts invisible to the eye. 



Quantities of air-bubbles rose to the surface, imtil the river became 

 covered with foam, and presented the appearance of simmering water. 

 The temperature of the water where this appeared was 100° to 105° 

 Fahr., that of the remainder of the river being 80°. 



The most remarkable circumstance was the effect produced on the 

 bed of the river. Mounds of mud were raised several feet above the 

 surface of the water, and appeared as if a huge bank of mud had 

 been permanently thrown up in the midst of the river. 



The temperature of the soil thrown up was 60° to 65° only ; but 

 it smelt so offensively as to taint the atmosphere for a considerable 

 distance in the immediate neighbourhood. 



After having been thus disturbed for the space of four hours, the 

 bed subsided, and the river again resumed its ordinary appearance. 



I trust this imperfect description may enable you to judge as to 

 the cause of so curious a commotion. Here it is generally looked 

 upon as being of volcanic origin. 



November 20, 1861. 



Charles Sanderson, Esq., C.E., Engineer-in-Chief of the Bombay 

 and Baroda Bailway, Surat, Bombay ; Ralph Tate, Esq., Teacher of 

 Natural Science, Philosophical Institution, Belfast ; James Ray Eddy, 

 Esq., C.E., Carleton Grange, Skipton ; Henry "Worms, Esq., of the 

 Inner Temple, 272 Park Crescent, Portland Place ; and Haddock 



that there is any good generic distinction ; though I admit that the form of the 

 aperture suggests the possibility of affinity to Bulimus as well as to Pupa. 



Mr. J. G. Jeffreys, F.G.S., who considers the shell to be a true Pupa, has kindly 

 directed my attention to traces of ridges observable on the columella of one spe- 

 cimen, and which he regarded as corresponding with the screw-like plates in the 

 young of Pupa umhilicata and P. ringens. This appearance I have observed in 

 specimens now in my possession ; and at one time I supposed that I had made 

 out a distinct tooth ; but, not finding this in other and less compressed indivi- 

 duals, I concluded that it was an effect of pressure; in which, however, I may 

 have been mistaken, as Mr. Jeffreys states that these processes have no connection 

 with the teeth in adult specimens, and that even the toothless variety of P. umbili- 

 eata is furnished with them. 

 ' * Dated " ManUla, June 1861." 



