Aug. 3 i, i83S.] 



SCIENTIFIC NEWS. 



i97 



examined under a microscope. Examined as a hand 

 specimen, many, perhaps the greater part, show no struc- 

 ture and we are tempted to throw specimens away as 

 "only a piece of limestone." But make a thin section, 

 which is not a difficult matter, and the rock will tell a 

 different tale. Some beds are made up of little else 

 than the valves of Ostracoda, a tribe of small Crustacea, 

 which are allied to what are commonly known as 

 water-fleas. The bodies of these little creatures 

 were protected by bivalve shells, containing car- 



Fig. 1. 



Section of a piece of Limestone from the Lower Limestone Shales. 



X 40 diams. Shows it to be made up of the valves of Ostracoda. 



bonate of lime, and on the death of the organism 

 the shells collected on the sea floor in such vast 

 numbers that whole beds of limestone are made up 

 of them. A micro-photograph from a piece of this lime- 

 stone, from the Lower Limestones of Clifton, is repre- 

 sented in Fig. 1, and it is seen to be full of the valves 

 of Ostracoda, appearing, of course, in section. 



Associated with the Ostracoda, in the Lower Limestones, 



Fig. 3. 



Section of the Middle Limestone at Clifton, x 40 diam. Shows 

 it to be made up of Forminifera and the very minute Calci- 

 sphrera, represented by the circular bodies. 



are the remains of Encrinites, better known as Sea 

 Lilies, of which illustrations can be seen in most text- 

 books of geology. 



They consisted of a stalk or stem, constructed of 

 circular joints, which, fitting one into another with most 



beautiful adjustment, give the requisite flexibility and 

 strength to enable the Encrinite to bend about in all 

 directions. This stem supported a cup-like body or 

 calyx, as it is termed, which was constructed of cal- 

 careous plates. From the margins of the calyx 

 five to seven jointed arms radiated, and from these other 

 jointed projections, called by Miller tentaculated 

 fingers. With these the creature seized its prey, 

 which it conveyed to the mouth, located in the centre 

 of the calyx. Encrinites must have been most abun- 



Fig. 2. 



Section of the Black Rock Limestone of Clifton. X20 diam. Shows 



it to be made up of the joints of Encrinites. 



dant during carboniferous days, and the joints and plates 

 composing their structure collected on the sea floor 

 in such vast numbers that extensive masses of limestone 

 are made up of them. A notable instance of this is the 

 "Black Rock," the upper division of the Lower Lime- 

 stones at Clifton, which is about 490 feet thick (fig. 2.) 



To see the Encrinital remains in the Black Rock 

 does not necessarily require a microscope, and no diffi- 



Fig. 4. 



Section of Pennant Sandstone, x 20 diam. Shows it to be made up 



chiefly of grains of sand. 



culty will be experienced in finding confirmation in 

 hand specimens, especially if polished. This limestone 

 is also remarkable for the fish remains which it has 

 yielded, some of which were figured by the celebrated 

 naturalist, Agassiz. Proceeding further up the Gorge, 

 we pass over other limestones, one of which shows 



