Vol. xlvi.] philosophical tbansactions. 107 



formation is got, he calls it, scolopendrae aquaticae scutatae affine animal pe- 

 trifactum. 



The Description and Figures of a small flat Spheroidal Stone, having Lines 

 formed on it. By C. Mortimer, M. D., and Sect. R. S. N° 496, p. 602.^ 



Mr. Peter Collinson produced, at a meeting of the r. s. on Nov. 8, 17S0, a 

 very curious spheroidal stone, about 4 inches diameter, of a chocolate colour, 

 marked with 4 white lines, about the breadth of a horse-hair, encompassing the 

 whole stone, like the meridians on a globe ; but, instead of crossing one another 

 in a point, as they do, on the globe, these are connected by a short transverse 

 line. 



Dr. M. also lately received, by a friend, from the isle of Shepy in Kent, a 

 small stone, with similar lines on it. This is only i of an inch in diameter, of a 

 brown colour, and of the consistence of marble. As a description in words does 

 not convey so clear an idea as an exact drawing, he has given representations of 

 this stone in different views ; as at tab. i. fig. IQ, 20, 21, 22. 



Fig. 19 represents the top of the stone, on which the lines are most regular, 

 being depressed into the stone, and of the same colour with it. a, c, d, e, are 

 the 4 principal lines, answering to those on Mr. Collinson's stone, and are con- 

 nected, as in his, by the transverse line g h. The line b is an irregularity in 

 this stone, and so is f, which are not in the other ; these irregular, or super- 

 numerary lines being continued to the other hemisphere. 



Fig. 20, or bottom of the stone, make the directions of the other lines very 

 irregular, as may be seen in the figure ; only the lines c, d, and e, being con- 

 nected by the transverse line g h. which here stands at right angles with that 

 in fig. 19. 



The following figures represent the section of the stone through its equator, 

 as nearly as possible ; only the mill cut away the substance to about the thick- 

 ness of a shilling. In these sections the ramifications appear quite white. Fig. 

 21 shews the section of the upper hemisphere, as fig. 22 does that of the lower 

 hemisphere ; in both of which the letters of reference answer to those in the 

 other figures, shewing where the outside lines abut on these sections. 



An Explanation of the foregoing Figures Collected in PI. 1 . 



9. The face of the Dudley fossil rolled up; 10, the back of the same; 1 1, 

 the fore and under part, with the tail folded close under the jaw ; 12, Dr. Shaw's 

 fossil half extended ; 13, the face of the same; 14, the under side of the same, 

 Tjeing folded but half way, leaving a space between the jaw and the tail ; 1 5, 

 Dr. Pocock's extended fossil, the back uppermost ; 1 6, a side view of the same ; 



p 2 



