150 Geological Society. 



invariably detected, a few feet above the base of the lias clay, a 

 thin band of white sandstone containing the same shell. 



The bone-bed at Axmouth, Watchett, Aust, Westbury, and other 

 southern localities, occupies precisely the same geological position, 

 or a few feet above the top of the greenish marls which terminate 

 the New Red system, though much more rich in organic remains ; 

 and Mr. Strickland draws attention to this remarkable instance of a 

 very thin stratum ranging over a distance of about 112 miles. 



The great abundance of fossils in some parts of this stratum the 

 author considers an indication that a much longer period probably 

 elapsed during its deposition, either on account of the clearness of 

 the water or of a gentle current which prevented the precipitation of 

 muddy particles, than while an equal thickness of the less fossiliferous 

 clays above or below it was accumulated. 



The list of organic remains given in the paper includes scales 

 of Gyrolepis tenuistriatus ? and Amblyurus ; teeth of Saurichthys api- 

 calls, Acrodus minimus, Hybodus minor, Pycnodus ? ; others bearing 

 an analogy to those of Sargus ; portion of a tooth with two finely 

 serrated edges, and considered as probably belonging to a saurian 

 allied to the genus Palceosaurus ; a tooth of Hybodus De la Bechei 

 (H. medius, Ag.), a ray of Nemacanthus monilifer ; small vertebra 

 of a fish ; bones of an Ichthyosaurus ; coprolites ; and the casts of the 

 bivalve before mentioned. 



Mr. Strickland next alludes to Sir Philip Egerton's paper on the 

 Ichthyolites of the bone-bed, and he states that the bed cannot 

 be of the age of the muschelkalk, as it overlies the red and green 

 marls, which he considers to have been satisfactorily shown to 

 be equivalent to the Keuper sandstein of Germany; and that 

 the occurrence of muschelkalk fishes associated with lias Ichthy- 

 olites only justifies the inference that certain species survived from 

 the period of the muschelkalk to that of the bone-bed. There 

 are yet stronger grounds, Mr. Strickland states, for placing the 

 bone-bed in the liassic series in the remarkable change a few feet 

 below it, from black laminated clay to compact " angular " marl, 

 greenish in the upper part and red below ; and he adds, the trans- 

 ition is so sudden that it may be defined within the eighth of an 

 inch ; moreover no marl occurs above the line nor black laminated 

 clay below it ; and although, in the case of the bone bed, an arena- 

 ceous deposit similar to the Keuper sandstein is repeated, accom- 

 panied by some triassic organic remains, yet, the author adds, this 

 does not invalidate the evidence of the commencement of a new 

 order of things, or of an interesting passage into the liassic series 

 from the triassic system. 



Lastly, Mr. Strickland notices the occurrence of precisely analo- 

 gous bone-beds in the Upper Ludlow rock, described by Mr. Mur- 

 chison in the ' Silurian System' (p. 198), and in Caldy Island, near 

 the junction of the carboniferous limestone with the old red sand- 

 stone ; and he offers some remarks on the bone-beds being found in 

 all the three cases near the passage from one great geological system 

 of rocks to another. 



