Miscellaneous. 231 



4. ' Questions relating to the Formation of Coal-Seams, including 

 a New Theory of them : suggested by Field and other Observations 

 made during the past decade on both sides of the Atlantic' By 

 W. S. Gresley, Esq., F.G.S. 



A number of new facts are described, and the bearing of these 

 and of previously recorded facts upon the origin of coal is discussed, 

 special reference being made to the Pittsburgh Coal. The Author 

 lays stress on the stratification of coal, the sharp line of demarca- 

 tion between coal and underclays, the character of the plants in the 

 underclays and their asserted root-nature, the existence of partings 

 in such seams as the Pittsburgh Coal, which partings sometimes 

 contain Anihracosia, and really separate the coal into distinct seams. 

 He describes the occurrence of ' rods ' of vegetable origin whose 

 exact nature is not known, which, with ferns, he suggests con- 

 tributed largely to the formation of some coals. He maintains that 

 the evidence points to the formation of coal on the floor of an ex- 

 panse of water, by vegetable matter sinking down from floating 

 ' islands ' of vegetation, which may have been of very large size, and 

 enumerates cases of such ' islands ' or ' rafts ' of vegetation which 

 have been described as existing in modern times. 



MISCELLANEOUS. 



Researches on the Structure, Organization, and Classification of the 

 Fossil Reptilia. — Part IX. Section 4. On the Gomphodontia. By 

 H. G. Seblet, F.R.S. 



The Gomphodontia is a group of Anomodont reptiles characterized 

 by Theriodont dentition, in which the molar teeth are expanded 

 transversely, more or less tubercuiate, and have the crowns worn 

 down with use, as in ungulate and other mammals. The orbit of 

 the eye is distinct from the zygomatic vacuity, which is conditioned 

 as in the Cynodontia, there being a long narrow parietal crest 

 dividing the temporal vacuities. There are two well-defined occipital 

 condyles united at the base, in a way that is closely paralleled in 

 some mammals. The occipital plate is triangular, as in mammals, 

 with no perforation except the foramen magnum. A deep superior 

 notch defines the occipital plate from the lateral external squamosal 

 bar. The malar bone, which forms the larger part of the zygoma, 

 behind the orbit has a slight descending process, which varies in 

 development. The hard palate terminates transversely in the middle 

 length of the molar teeth. There is a descending transverse pala- 

 tine arch situate behind the orbits. The incisor teeth are small and 

 pointed ; the canine teeth may be inconspicuous, but are usually 

 large, compressed, and serrated ; the premolars are small, circular, 



