Prof. Dr. Parlotc — OUgocene Sandstone in Neocomian Clays. 51 



availing myself of his advice and his large and fine collections. 

 Prof. von. Koenen also recognized the fauna of Yavley as Lower 

 Oligocene. I am able now to give the following list of the fossils 

 of this fauna : 



Voluta sntumlis Nyst. 



Pectunculiis tenuisulcalus v. Koenen. 



Astarte Bosqueti Nyst (v. Koenen), or another very closely allied 

 species differing from Astarte Bosqueti only by the lateral teeth 

 being somewhat shorter. 



Ostrea ; many small specimens partly resembling young specimens 

 of Ostrea flabellula, and partly like the young of Ostrea Queteleti 

 Nyst (v. Koenen). 



Nucula, cf. BowerbarJcii Wood (non Dixon). 



Natica, cf. hantoniensis Pilk. 



Acirsa, probably a new species allied to Acirsa angusta (v. 

 Koenen). 



Cases are well known in which small bands of sedimentary rock 

 have been jammed between rocks of another geological age. Such 

 occurrences have been observed in several countries by many 

 geologists, especially in regions broken by numerous and compound 

 faults, as for instance, in tbe cases of the bands and pieces of Jurassic, 

 Cretaceous and Tertiary rocks jammed between the Triassic rocks of 

 Middle German}'. 



The Neptunic dike of Alatyr cutting an area of undisturbed 

 stratification cannot be compared with such tectonic wedges, to which 

 latter, indeed, the term Neptunic dike cannot strictly speaking- 

 be applied. We are acquainted with other t3'pes of veins or 

 pockets cutting sedimentary strata and filled by another sedimentary 

 or fragmental mass ; such are the veins and ' pockets in the 

 Cretaceous Limestone between Lausanne and Yverdon in Switzer- 

 land (Poehes siderolitiques of Mouremont). Of similar character 

 are the veins and dikes in the Carboniferous Limestone of the eastern 

 border of the Mendip Hills filled by yellow marly conglomerate 

 witli Triassic fossils. In the same country (near Hoi well, about 

 five miles from Frome) there are still more interesting dikes cutting 

 into the Carboniferous Limestone, formed of Liassic conglomerate 

 with marine fossils. These latter were described by Mr. Charles 

 Moore in the Quart. Journ. of Geol. Soc, vol. xxiii, 1867. They 

 have been considered as fissures in the Carboniferous Limestone, 

 when that rock formed first a shore pounded by the breakers of 

 the Liassic sea and afterwards the floor with open fissures of this 

 Liassic ocean. 



Sandstone dikes, more or less closely resembling our Alatyr dike, 

 have been described by many authors. Thus Mr. H. Strickland 

 (Trans. Geol. Soc. Ser. ii, vol. v, p. 599) has described four dikes 

 penetrating into Lias shale at Ethie, near Cromarty in Ross-shire, 

 of which two are parallel to the stratification of the Lias shale, but 

 the other two send off branches in various directions ; no fossils 

 have been noticed in the substance of the dikes, and the period 

 of insertion of the sand into the fissures is undeterminable. Mr. 



