440 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



Scutella Jonesh Edward Forbes. 

 Body plane, shield-shaped, subpentangular, with sides and posterior 

 margin undulated ; angles obtuse. 



Back centrally slightly convex, interambulacral spaces depressed ; ambu- 

 lacral spaces broad, somewhat convex, with parallel sides. Avenues petaloid, 

 with their inner margins nearly straight. Pairs of pores in each avenue 37, 

 united by oblique lines. 



Oral surface concave, with five deep furrows radiating from the mouth to 

 the margin. 



Margin thick, rounded. 



Lat. 2-jL. Ion. 2{9. crass, max. T 4 2 . 

 This species appears to have been marked with spots. 

 Locality. — Jacksonboro'. 



I have no doubt that all the sandy soil on which the long-leaved 

 pitch pine grows in the neighbourhood of Jacksonboro' belongs 

 to the burrstone formation, consisting of sand, ferruginous sand- 

 stone, and red loam, and although it is rare to find the limestone 

 and marl exposed to view, I believe it to be everywhere subjacent. 

 For we meet not unfrequently in Scriven, and several of the ad- 

 joining counties, with lime-sinks, or deep depressions, more or less 

 circular in shape, in the vertical walls of which we observe sec- 

 tions of the horizontal beds of sand and mottled red and yellow 

 loam and clay. As the water does not stand in these sinks, there 

 is evidently a subterranean drainage, by which the loose sand has 

 been carried down, and the surface undermined, as before de- 

 scribed at Cave Hall. I saw several lime-sinks near Jackson- 

 boro', and one about 16 miles south of Millhaven, on the east 

 side of the road to Savannah, at Reeve's mill. It was 60 paces in 

 circumference, and 80 feet in depth, and the beds gone through 

 consisted of yellow and deep-red sand, in' some parts ferruginous, 

 with beds of mottled red and white steatitic clay. 



