JURASSIC OF THE PAEIS BASIN. 



509 



ting by the massive rocks of the Nerinsean series as seen on the 

 opposite side of the river. Succeeding these at once are more marly 

 rocks than any seen before ; in fact they are alternations of marls and 

 flaggy earthy limestones, with here and there a bed of oolitic rock, 

 a lumachelle of Exogyra bruntutana, or a lithographic limestone. The 

 thin beds having their surfaces crowded with Astarte supracorallina, 

 indicate with certainty the horizon. Rocks of this description occupy 

 the country for a distance of five miles, till the lowest Yirgulian 

 lumachelle is reached, and seem to be rather uninteresting and barren. 

 Nevertheless Buvignier describes the lithographic stones as massive, 

 and overlain by an irregular pisolite having the fossils as casts, in- 

 cluding Diceras and Cardium Buvignieri, a species which appears to 

 be not different from 0. corallinum. This would seem to indicate a 

 repetition of the Diceras-beds at a higher horizon than the first, namely 

 immediately beneath the Yirgulian; and the list of fossils given as from 

 the upper portion of the Astartian limestones contains several species 

 usually of a lower horizon, such as Lima cequilatera, Pecten articula- 

 tus, Chemnitzia lieddingtonensis, Natica globosa, &c. These pisolites 

 are said to occur in the very district now under notice ; but though 

 the various sections were duly searched, no such rock was observed 

 in the required position. At Baleycourt quarries were seen in which 

 the stone was very rubbly ; but it had the aspect entirely of a rede- 

 posited material with the fossils in it remanie, and not at all like the 

 true Diceras-beds of the Haute- Marae. With this exception, no 

 change in the character of the rocks is observable till the lumachelles 

 with Exogyra virgida are reached. If therefore any portion repre- 

 senting the Pterocerian beds is to be found, it must be sought either 

 in the beds containing E. virgida or in the lithographic limestones 

 below. The latter are credited with an enormous thickness (400 feet), 

 and obviously include much more than is usually placed in the 

 Astartian beds. In point of fact, there seems little to characterize 

 the beds here; and their subdivisions must be left somewhat 

 doubtful. 



In the Yirgulian marls which follow we have fortunately an admir- 

 able landmark, both because the abundance of the little oysters (which 

 in themselves make half the bed) renders these marls immediately 

 recognizable, and because the variety of their other fossils gives 

 good materials for correlation. At the cutting of Mxeville the dark 

 marls with E. virgula occupy the lower 12 feet, and white chalky 

 limestones the upper 20 feet ; neither therefore is seen in its full 

 thickness. For a considerable distance to the west, alternations of 

 these two forms recur, the marls being the last seen beneath the 

 overlying lithographic limestone. The whole series does not appear 

 to occupy so great a thickness as the lower Astartian beds. The white 

 limestones are extremely fossiliferous, the most abundant shells being 

 PleuromyaVoltzii,Plioladomya acuticosta,Cuculla?a texta, a,nd Terebra- 

 tida bisuffarcinata. The other fossils observed were Pterocera Ponti, 

 Chenopus musca, Chemnitzia gigantea, Thracia lata, Mactromya ru- 

 gosa,Ceromya excentrica, Cardium Bannesianum?, Trigonia Merian 

 T. Juddii, Pinna granulata, and Nucula Menkei and Astarte supra- 



