Occurrence of Remains of Small Crustacea in the 



PROTEROZOIC (?) OR LOWER CAMBRIAN (?) ROCKS OF 

 REYNELLA, near ADELAIDE. 



, By Professor T. Edgeworth David, K.B.E., C.M.G., 

 D.S.O., B.A., F.R.S., Hon. D.Sc. Oxford and Manchester. 



[Read November 10, 1921.] 



Plate II. 



Description of Fossils. 



Through the kind assistance of Professor Walter Howchin, 

 F.G.S., I was enabled, over a year ago, to examine some 

 good sections of the siliceous limestones underlying the 

 Brighton limestone, at Reynella, 17 miles southward of Ade- 

 laide. The siliceous limestone, as exposed in several of the 

 small quarries belonging to the South Australian Portland 

 Cement Company, and nearest to Reynella, on the left bank 

 of the Field River, shows curious small ochreous bodies in 

 a bluish-grey ground-mass. The limestone is mostly oolitic 

 in structure. These yellowish-brown to ochreous bodies are 

 seen under the microscope to be distinctly of organic origin, 

 and there can be little doubt that they are referable to some 

 kinds of minute Crustacea. Their general appearance is shown 

 on fig. 3 of pi. ii. 



The larger object shown on the left side of fig. 3, and 

 about 2 mm. in length, has all the appearance of being a 

 swimming paddle. The object marked (f) is possibly part 

 of a spiral gill. The remainder of the objects in fig. 3 are 

 probably locomotary appendages. 



Fig. 2 probably represents a small carapace. Fig. 1 is 

 the only specimen which shows some bilaterally symmetrical 

 organization. At the top are traces of what may be antennae 

 or antennules, followed iDelow by two pairs of small processes, 

 and below these is a pair of stouter appendages, probably 

 claws. The spiral object to the right of the claw ( ?) may be 

 one of the spiral gills. A pair of possible parapodia follow, 

 and then two fragments of what may have been a somite, or 

 body ring. The remainder of the dark objects seen are quite 

 problematical. Similar but less well-preserved objects occur 

 in the overlying Brighton limestone. 



