42 Proceedings of the Royal Society of Victoria. 



By refei'ence to the list of shells given in the former paper as 

 occurring in the shelly marl it will be noticed that neither Cor- 

 bicula nor Tatea was included. These shells did not occur in the 

 marl as far as observed. The black clay they were found in was 

 then regarded as being probably the littoral portion of the 

 estuarine deposits, and tliat opinion has now been confirmed 

 as far as relates to this locality. The occurrence in this clay of 

 Tatea and Corbicula, and their association with Nassa and 

 Mactra prove that this spot was near the margin of the mouth 

 of the old Yarra, in water greatly affected by the rise and fall 

 of the tide. 



Since the former paper was published, work of an intermittent 

 character has been done in these Yarra Improvements. The 

 cuttings have been carried about 165 yards past Punt Road foot- 

 bridge, and deepened on the western side. The strata on the 

 western side revealed up to the present time consist of 

 15 feet of alluvium, the lower portion being a yellowish-grey 

 loamy clay with pieces of carbonised wood, overlying 6 feet of 

 dark bluish-grey stiff clay with pieces of wood. No shells of 

 any kind are observable. 



[On the east of the bridge the cutting ends in grey indurated 

 claystones and massive beds of grey mudstones. On the northern 

 side these Silurian rocks are covered by 4 feet of alluvium at the 

 eastern end, but at 50 yai'ds west they disappear beneath about 

 20 feet of alluvium. On the southern side they show at the 

 surface for 75 yards from the end. The beds dip 80° at 47°. 

 The overlying beds consist of grey and brown loam, 12-16 feet^ 

 resting on 8 feet of dark and light coloured loam and clay, the 

 lower portion of which contains a large number of angular frag- 

 ments of the Silurian rocks. An interesting dyke occurs in the 

 Silurian strata in the southern bank. It is from 16 inches to 

 2 feet wide, bears N.65°W., and runs parallel with the section. 

 At the western end it shows at the surface, while at the eastern 

 it is split into two prongs, one 3 inches, the other 8 inches thick. 

 In the face here numerous thin bands and threads branch oflF and 

 intersect the strata along the joint planes. About 20 feet west 

 of this point a prong runs N. from the dyke. The rock is greatly 

 decomposed, but is evidently of a granitic nature, and, as seen, 

 consists of clay and large crystals of biotite up to 1 inch in 



