348 Mr. Williamson oji the Limestones 



cartilage when rotated with the thyroid, whereby the 

 antero-posterior diameter of the larynx is enlarged 

 and the vocal ligaments stretched from a d io ae. 

 f. The chink between the thyroid and cricoid cartilages. 

 The dotted line represents the closing of this chink 

 when the cricoid is rotated on the axis of motion of 

 these cartilages at the-point d. 

 Bernard Street, Brunswick Square, June 7, 1836. 



LXVIII. On the Limestones found in the Vicinity of Man- 

 chester. By W. C. WiLLTAMSON, Curator of the Museum of 

 the Manchester Natural History Society. 



[Continued from p. 249, and concluded.] 

 Sect. VII. — Other Localities isohere Limestones are exposed. 



AT two more localities limestones have been pointed out to 

 me by Dr. Charles Phillips, who has contributed so much 

 towards the elucidation of the geology of this district; both of 

 these were exposed by the cutting of the Liverpool and Man- 

 chester Railway. One of these is at the base of the Sutton 

 inclined plane on the Manchester side, and the other near 

 Whiston, on the opposite side of the hill, forming two of the 

 points which guided Mr. E. Hall in laying down the range of 

 the magnesian limestone, with which he confounded them. 



That at Whiston is exposed for about seventy yards, and 

 forms a seam six feet thick, but which never rises more than 

 nine feet above the level of the railway and is covered for some 

 extent by a series of solid sandstones. The top of the lime- 

 stone consists of a greenish conglomerate, below which is pre- 

 sented the reddish conglomeroid structure peculiar to the Ard- 

 wick limestones, and the lower portion of the seam is composed 

 of the solid gray limestone common at the above locality. 



From its so strongly exhibiting the peculiar mottled ap- 

 pearance, I am of opinion that it will correspond with the 

 uppermost or four-feet seam at Ardwick. This is in some 

 measure confirmed by the occurrence of the same minute tur- 

 binated shells (Planorbis ?) found in the Ardwick series ; but 

 as no borings have been made on the spot, I cannot be certain 

 as to what exists below. 



The limestone at Sutton I cannot identify with any exposed 

 at Ardwick, although in its appearance and fracture it resem- 

 bles the thin one of two feet below the main limestone on the 

 bank of the Medlock. It is only about a foot thick, and rests 

 upon a long range of the coal shales, which are very well ex- 

 posed, exhibiting many partial faults and thin coal seams. 



As I before described, at Collyhurst we have the magnesian 

 limestone laid bare for a small space ; and about half a mile 



