338 R. I. MuRCHisoN, Esq. and H. E. Strickland, Esq., on the 



of sandstone subordinate to it, which sandstone is separated, by at least 600 

 feet of marls, from the great mass of the underlying new red sandstone. 



Organic Remains of the Keuper. (Plate XXVIII.) 

 When our examination of this tract commenced, it was a prevalent belief, 

 that as no fossils had ever been found in the red marl formation, so was it hope- 

 less to look for them. We have now to announce the existence of fishes, shells, 

 and the impressions of footsteps of probably a Batrachian animal. The locality, 

 in which organic remains were first discovered in the Keuper sandstone, is at 

 the Burge-hill quarries, before mentioned. Here, they are by no means plen- 

 tiful, but after considerable search a long Ichthyodorulite was found*, (fig. 3.) 

 with numerous casts of small bivalve shells (fig. 4,). This Ichthyodorulite 

 manifestly belongs to an undescribed species of the genus Hyhodus, (Agassiz,) 

 and it is therefore exceedingly interesting in showing, that the same types of 

 organization, which prevail in the lower lias, existed during the deposition of 

 the upper part of the new red system. The dentated posterior margin of the 

 spine is unfortunately wanting, but sufficient characters remain to warrant us 

 in regarding it as a new species. It is remarkable for the straightness of the 

 anterior margin, which hardly deviates one-eighth of an inch from a straight 

 line. It appears to have been of a remarkably taper form, but from the loss 

 of the hinder margin the diameter from front to back cannot be determined. 

 The transverse diameter at the larger end is about three-eighths of an inch, and 

 the total length is five inches. The longitudinal costce are smooth, rounded, 

 regular, and closely packed ; at the larger end six of them cover a quarter of 

 an inch (i.e. their diameter is one twenty-fourth of an inch). We propose to 

 name this species Hyhodus keuperinus. 



The bivalve shells, (Plate XXVIII., fig. 4.) appear to be the Posidonomya 

 minuta of Bronn (Lethcea Geognostica, page 164, PI. XL, fig. 22.), or the 

 Posidonia minuta of Goldfuss {Petrefacten, PI. CXIII., fig. 5.) and of Zieten 

 {Versteinerungen Wiirttembergs, PI. LIV., fig. 5.)f . 



In Germany, this shell is stated to pervade the new red system from the " Keu- 

 per" to the " Bunter sandstein" inclusive, but in this country, it appears pecu- 

 liar to that band of sandstone, which we have proved by stratigraphical evidence 

 to represent the upper formation. It is indeed a very characteristic shell, for, 



* By Mr. Strickland. 



t Bronn has changed the generic name to Posidonomya, the term Posidonia being pre-occupied 

 in botany. Capt Portlock has lately detected this shell in the new red sandstone of Roan Hill, 

 near Dungannon, Ireland. 



