Midland Scientijic Association. 377 



to the speculations of the mathematician and astronomer (reference 

 ■was here made to Mr. Croll's calculations) , at the lowest estimate, the 

 extinct Mammalia, and some of the beds in the Bath basin in which 

 they are found, must be from 80,000 to 240,000 years old. H.H.W. 



Midland Scientific Association. — A meeting of this Association 

 was held on April 26th, at the Bank House, Burton-on-Trent. 



1. Mr. F. Di'ake exhibited and gave a short account of some human 

 bones, consisting of a skull and some other portions of the skeletons, 

 which he had obtained from a gravel pit at Hinckley, near Leicester, 

 at a depth of 16 feet below the surface. The remains appeared of 

 considerable antiquity, but there were not sufficient data given by 

 which to assign any definite age to them. The drift gravels of the 

 Trent have been subjected to considerable disturbance, and it was 

 stated that tobacco pipes had been found at a depth of six or seven 

 feet in the Trent Valley. 



2. Mr. James Plant read a paper " On the so-called Pseudomor- 

 phous Crystals of Chloride of Sodium, found in the Upper Triassic 

 rocks of Leicestershire and the adjoining counties." Mr. Plant gave 

 Bischof's definition of the term pseudomorphous, stating that it is 

 applied to such minerals as possess geometrical forms foreign to 

 themselves, and acquired in a way entirely different from crystalliza- 

 tion. They are divided into two classes : first, alterative-pseudo- 

 morphs, produced either by removal, addition, or exchange of con- 

 stituents ; second, displacement-pseudomorphs, produced by incrusta- 

 tion or by replacement. But the pseudomorphs found in the Triassic 

 rocks belong to neither of these classes ; they are produced by a de- 

 position of substances in cavities left in rocks by the solution of im- 

 bedded crystals, analogous to casting in a mould, thus, though the 

 outside of the cast assumes all the minute appearance of a crystal, 

 the inside possesses none of the properties of a true crystal, having 

 no cleavage planes, axes, etc. Mr. Plant then stated that the pseudo- 

 morphs illustrating his paper were first found near to the Spinney 

 Hills, east of Leicester, in a thin yet persistent band of grey sand- 

 stone, varying in thickness from six inches to as many feet ; they 

 are likewise found in shales, with fine partings of greenish marl, 

 and at these partings sticking at all angles in the sandstone and pro- 

 jecting into the marl are the pseudomorphs. This thin seam of 

 sandstone is not far from the edge of the Lower Lias, and lies above 

 the Gypsum bed, and must not be confounded with the Upper Keuper 

 sandstone, which lies below the Gypsum. This bed of thin sand- 

 stone, with its accompanying pseudomorphs, occurs near Elton, over- 

 lying the Gypsum, and close to the edge of the Lias ; here the salt 

 casts were found associated with iron pyrites, the pyrites being in- 

 crusted upon them. At Orton-on-the-Hill, the pseudomorphs are found 

 in the Upper Keuper sandstone before mentioned, — in this locality it is 

 a hard rock, varying from eight to twelve feet in thickness; some of its 

 beds are covered with ripple marks, and in the ripple marks the casts 

 occur as simple square figures having no relief. Mr. Plant obtained 

 his finest pseudomorphs in the Upper Keuper sandstone at Chilwell, 



