442 FOSSIL TEETH IN NEW RED SANDSTONE. [Ch. XXII. 



and the Bone-bed series of many geologists, as well as the Khsetic beds 

 of Mr. C. Moore, it has lately been named the Penarth beds by the 

 Government surveyors of Great Britain, from Penarth, near Cardiff, 

 in Glamorganshire, where these strata are finely exhibited in the 

 sea-cliffs. 



The best-known member of the group, a thin band or bone-breccia, 

 is conspicuous among the black shales in the neighborhood of Axmouth, 

 in Devonshire, and in the cliffs of Westbury-on-Severn, as well as at 

 Aust and other places on the borders of the British Channel. It 

 abounds in the remains of saurians and fish, and was formerly classed 

 as the lowest bed of the Lias ; but Sir P. Egerton first pointed out, in 

 1841, that it should be referred to the Upper New Ked Sandstone, 

 because it contained an assemblage of fossil fish which are either 

 peculiar to this stratum, or belong to species well known in "the Mus- 

 chelkalk of Germany. These fish belong to the genera Acrodus, 

 Hybodus, Gyrolepis, and Saurichthys. 



Among those common to the English bone-bed and the Muschelkalk 

 of Germany are Hybodus plicatilis (fig. 480), Saurichthys apicalis (fig. 

 481), Gyrolepis tenuistriatus (fig. 482), and G. Albertii. Eemains of 

 saurians, Plesiosaurus among others, have also been found in the bone- 

 bed, and plates of an Encrinus. 



Fig. 481. Fig. 482. 



Hybodus plicatilis. Teeth. Bone-ted, JilmM^WS^ 



Aust and Axmouth. ffi^frr^ihffr^ 



Saurichthys apicalis. Gyrolepis tenuistriatus. 

 Tooth; nat. size, and Scale; nat. size and 

 magnified. Axmouth. magnified. Axmouth. 



In certain gray indurated marls below the bone-bed, Mr. Dawkins 

 found, at Watchett, on the coast of Somersetshire, in 1863, a two-fanged 

 molar tooth of a fossil mammifer of the Microlestes family. Mr. Chas. 

 Moore had previously discovered twenty-seven teeth of mammalia of the 

 same family near Frome, in Somersetshire, in the contents of a vertical 

 fissure traversing a mass of carboniferous limestone. The top of this 

 fissure must have communicated with the bed of the Triassic sea, and 

 probably at a point not far from the ancient shore on which the small 

 marsupials of that era abounded. 



The strata of red and green marl, which follow the bone-bed in the 

 descending order at Axmouth and Aust, are destitute of organic remains : 

 as is the case, for the most part, in the corresponding beds in almost 

 every part of England. But fossils have been found at a few localities 

 in sandstones of this formation, in Worcestershire and Warwickshire, 



