Ill REPORTS ON THE STATE OF SCIENCE. 



unci in strike with respect to the local Quarry Eidge Grit, and 1 have 

 secured a good photograph of that exposure also (Plate III., fig. 2). 

 The bedding, indicated by the direction of the hammer handles, and the 

 strikes of the rocks of both series are well shown. The dip of the upper 

 series is about 45° and that of the lower about 55°, and the dis- 

 cordance of strike amounts to about 30°. 



Relative Ages oj the Upper and Lower Groups at Robin's Tump. 



The Upper Comley (Middle Cambrian) age of the grits above the un- 

 conformity at Robin's Tump is shown by the fact that they afforded 

 the several specimens of Dorypyge Lakei (Cobbold) which I obtained 

 from one of the Grit beds near x*, on the section, and by the Parad- 

 oxides cheek from 29d alluded to above. 



The Lower Comley (Lower Cambrian) age of the lower beds at 

 Robin's Tump may, I believe, be regarded as established by the fact 

 that the dark calcareous bands present in them are identical in cha- 

 racter with those that form integral parts of the Lower Comley Sand- 

 stone series elsewhere (Excavation No. 30, Sheffield Report, and Exca- 

 vation No. 4, bed a, Dublin Report). The exact systematic position of 

 the calcareous bands of Robin's Tump in the Lower Comley series how- 

 ever is unsettled. No such band was seen in Excavation No. 1 (Dublin 

 Report), which exhibited some 50 feet of beds immediately below the 

 Olenellus Limestone of the Comley Quarry. It seems probable, there- 

 fore, that the horizon covered by the unconformity at Robin's Tump is 

 considerably below the top of the Lower Comley Sandstone. 



Supplementary Excavations in the Neighbourhood of 



Robin's Tump. 



Excavation No. 41, South-West of Hill House. 



At a point close to the letter R of the words ' Lower Comley Sand- 

 stone ' on the map (see Sheffield Report) a natural exposure of green 

 micaceous sandstone was opened up, and the following section of about 

 15 feet of beds, with a south-easterly dip of about 50°, was exposed. 



East End of the Section. 



ft. in. 



(a) Band of hard sandstone 



(b) Clayey material 9 



(f ) Rubbly sandstone with brown patches containing one or 



more species of Hyotithm 3 



(d) Band of clayey material 1 3 



(e) Rubbly sandstone 2 



(/) Sandy flags, splitting well, and showing tracks of organisms 



on the surfaces of the beds 9 



West End of the Section. 



The tracks &¥& well-marked depressions on the upper surfaces of the 

 beds, with corresponding raised casts upon the lower surfaces, and are 

 unlike anything I have yet seen in the Comley area. The burrows 



