426 ON FISH-REMAINS FROM BONE-BED AT ATTST, NEAR BRISTOL. 



stated that Sphenonchus always occurs on the head of Hybodont 

 fishes in the Secondary rocks. 



Mr. Tawney thought the Palaeozoic forms in the Aust bed are 

 fossils derived from the Carboniferous strata, and not, as Prof. 

 Seeley contended, surviving types. 



Mr. Longe stated that there is a great difference between the 

 contents of the bone-bed at Garden Cliff at Westbury and Aust Cliff 

 respectively. He thought the fossils in the bone-bed do not belong 

 to the period at which the materials were accumulated. 



Mr. Ussher thought that the working-out of the Rhsetic beds 

 might afford evidence of the unconformities due to changed condi- 

 tions of deposit. He alluded to an appearance of unconformity 

 between Rhsetic and Trias at Newark, where a thin band of derived 

 fragments occurred at the base of the former. 



Eev. H. "Winwood argued against the theory of the bone-bed 

 being a remanie bed from the fact of the delicate fossils in it not 

 being waterworn. 



The President thought that most of the fossils at Aust Cliff and 

 Westbury are not remanie, but are of the true Rhsetic age ; but 

 some Carboniferous forms are undoubtedly derived. The specimens 

 of Ceratoclus were not at all worn. The form called Sphenonchus 

 is certainly the head-spine of Hybodus, as proved by specimens 

 from Lyme Regis. I j , 



The Author stated that the details that he had given represented 

 the examination of only three collections, and that there yet remained 

 much work to be done in this field. 



