Dr. G. Henderson on Sand-pits, Mud-volcanoes, fyc. 149 



so far decomposed as to have lost almost every trace of its original 

 structure. He said that it had been suggested that the decomposi- 

 tion of small fish must have furnished the Gault with a large pro- 

 portion of that phosphatic matter which saturated the last-deposited 

 clay of the formation, and which served to fossilize the decaying 

 organisms imbedded in it. He supposes that the roughly cylin- 

 drical forms having a core of white chalk-marl with an outer an- 

 nular portion of coprolitic material are sponges. He said that he 

 had obtained from the calcareous portions of this deposit numerous 

 specimens of Foraminifera belonging to genera of which he gave a 

 list. He thought that the green grains are casts of Foraminifera. 

 He stated that he has obtained several glauconitic casts still coated 

 with the shells of the Foraminifera in which they were formed. In 

 conclusion the author pointed out the unreliable nature of the ana*, 

 lyses made of the green grains. 



June 5, 1872.— J. Gwyn Jeffreys, Esq., F.R.S., in the Chair, 



The following communications were read : — 



1. " Notes on Sand-pits, Mud-volcanoes, and Brine-pits met with 

 during the Yarkand Expedition of 1870." By George Henderson 

 M.D., E.L.S. 



The author described some very remarkable circular pits which 

 occurred chiefly in the valley of the Karakash river. These pits 

 varied in diameter from 6 to 8 feet, and were between 2 and 3 feet 

 deep, the distances between the pits being about the same as the 

 diameters. He accounted for the formation of the pits by supposing 

 that the water, which sinks into the gravel at the head of the valley, 

 flows under a stratum of clay, which prevents it from rising ; the 

 water in course of time, however, flowing in very varying quantities 

 at different periods, gradually washes away small portions of the 

 clayey band, when the sand above runs through into the cazity thus 

 formed, leaving the pits described by the author. The mud-vol- 

 canoes at Tarl Dab he accounted for by supposing that after a fall 

 of rain or snow the air contained in the water-bearing stratum 

 would get churned up with water and mud, and be ejected -as a 

 frothy mud, sometimes to a height of 3 feet ; while the brine-pits in 

 the Kara'iash valley he believed to be formed by the excessive rise 

 and fall in the level of that river at various times, which alternately 

 fills and empties the bottoms of the pits, and the water left in the 

 pits gets gradually concentrated by evaporation until a strong brine 

 remains. 



2. " On the Cervidaa of the Forest-bed of Norfolk and Suffolk." 

 By W. Boyd Dawkins, Esq., M.A., F.R.S., F.G.S. 



The author described a new fo":m of Cervus from the Forest-bed 

 of Norfolk, which he based on a series of antlers, and named C. ver- 

 ticornis. The base of the antler is set on the head very obliquely ; 

 immediately above it springs the cylindrical brow-tyne, which sud- 

 denly curves downwards and inwards; immediately above the 

 brow-tyne the beam is more or less cylindrical, becoming gradually 



