842 



DR B. N. PEACH AND DR J. HORNE ON 



the manse, about two miles above New Castleton, yielded the following assemblage of 

 lamellibranchs, with which Spirwbis is usually associated : — 



Spirorbis, sp. 

 Anthracomya subparallela. 



Aricidopedcn Geikici, Eth. jnr. M.S. 

 Udmondia josepha, De Kon. 

 Leiopteria, sp. 

 Modiola Macadami, Porfcl. 

 Myalina sublamellosa, Eth. jnr. 



„ Verueuili, M'Coy. 

 Naiadites, sp. 



Nuculana attenuata, Flein. 

 stilla, M'Coy. 



Protoschizodus axiniformis, Portl. 

 „ nuculoides, M'Coy. 



." . S P- 

 Sanguinolites roxbicrgeiise, Hind. 



Schizodus, sp. 



Tellinomorpha, cuneiformis, De Kou. 



The forms given in the foreooino; list are often associated with remains of the higher 

 Crustacea of the genera Palceocrangon, Anthrapalcemon, and Pseudogalathea, while 

 entomostraca are frequently abundant. Among the Xiphosura, Prestwichia and Cyclus 

 occur. Occasionally there is evidence of purer marine conditions, indicating incursions 

 of the sea, as we may gather from the presence of Lingula squamiformis, Discina 

 nitida, and more commonly Camarophoria crumena. Some of the beds of thin lime- 

 stone in this group are composed mainly of the remains of the last of these forms in 

 association with Athyris ambigua and Orthotetes crenistria. Such marked proofs of 

 more marine conditions are rare in the lower part of the Cementstone group, embracing 

 about 500 feet of strata ; but above that level they are more numerous. Indeed, from 

 the thickness of the marine limestones which have been worked in the upper part of 

 Liddisdale, in the valley of Larriston Burn, Thorlieshope, and near Dead Water, on this 

 horizon, it is clear that marine conditions must have lasted for considerable intervals of 

 time. This zone is characterised by a form of Syringothyris (Spirifera) cuspidata, 

 which, with one exception, has been found in this area only in this zone. The excep- 

 tion referred to occurs on a slightly higher horizon than the Larriston Burn limestone. 



A list of fossils is subjoined from the limestones of Thorlieshope and Larriston 

 Burn, which is sufficient to demonstrate that marine conditions prevailed during their 

 deposition. At the same time it may be observed that many forms which appear in the 

 marine limestones overlying the Fell sandstones are absent from this list. The abun- 

 dance of lamellibranchs and gasteropods in this marine zone below the Fell sandstones 

 seems to imply that a considerable amount of sediment was then present in the sea- 

 water. 



List of fossils from the marine limestones of Thorlieshope and Larriston Burn : — 



Ghcetetes tumiclus, Phill. 

 Palcvacis cyclostoma, Phill. 

 Syringopora ramulosa, Goldf. 

 Lithodrotion ju nceum , Flem. 

 Palcechiv us globulus. 

 Poteriocrinus crassus, Miller. 

 Spirorbis ambigtcus, Flem. 

 ^Entomostraca. 

 Athyris ambigua,, Sow. 

 ,, Roysii, Lev. 



Camarophoria crumena, Mart. 

 Lingula scotica, Dav. 

 Produdus longispinus, Sow. 



„ semirdicidatus, Mart. 

 Rhynchonella, sp. 

 Spirifera bisidcata, Sow. 



„ trigonalis, Mart. 

 Syringothyris (Spirifera) cuspidata. 

 Allorisma sulcata, Flem. 

 Aviculopcden ccelatus, M'Coy. 



