580 J. W. KIRKBY ON MARTN^E FOSSILS IN THE 



Sanguinolites subplicatus. 

 Schizodus Salteri*. 

 Bairdia nitida. 



prsecisa. 



Cythere superba. 



cypridiformis. 



Kirkbya spiralis. 



L ttorina scotoburdigalensis. 

 - " bilineata. 

 Macrocheilus ? striatulus. 

 Cypricardia bicosta. 

 Myalina modioliformis* 



sublamellosa. 



Pleurophorus elegans. 

 Sanguinolites abdensis. 



The repeated occurrence of bituminous shales and thin limestones 

 full of the carapace-valves of Ostracoda is another palseontological 

 feature strongly characteristic of the Calciferous Sandstones. The 

 species thus occurring are not many in number ; Leperditia OJceni, 

 var. scotoburdigalensis^ is the most common form ; and following it 

 in abundance are L. OJceni, var. attenuata, and Beyrichia subarcuata. 

 These Ostracods may or may not indicate a marine origin of the beds 

 in question. They are all found occasionally v^ith Myalina modio- 

 liformis, and the Leperditice are usually of marine habits ; and that 

 is about all that can be said on the matter. 



Of equally dubious origin are the numerous beds containing the 

 scales of small Ganoid fishes and the remains of Spirorbis carbon- 

 arius, which often occur with the Ostracoda, or with plants, and 

 sometimes with Myalina and other marine fossils — though when 

 such forms as Orthoceras and Schizodus come in with the latter, this 

 Spirorbis gives place to another representative of the genus, identical 

 with, or allied to, 8. globosus, M'Coy, and the fish-remains are 

 usually absent. 



It will have been observed that the groups or zones of fossils of 

 the preceding sections are not all equally marine. Thus zone 11 of 

 the Pittenweem and Anstruther section, which includes the remains 

 oi Lepidodendron and Carbonia, together with Myalina modioliformis, 

 can scarcely be looked upon as of so marine a character as the group 

 above, zone 10, which contains among its species representatives of 

 the genera Bellerophon, MurcMsonia, and Leda. The fossils of zone 

 11 and other kindred groups have been looked upon as marking marine 

 horizons mainly on account of the presence of M. modioliformis ; 

 and this sheU. I consider to have been a marine species, because it 

 is repeatedly found associated with Schizodus Salteri and other un- 

 doubted inhabitants of salt water, and because the other species 

 of Myalina known to me appear from the associated fossils to have 

 been of marine habits. Thus — 



Myalina sublamellosa, Eth., occurs in the thoroughly marine 

 groups of zones 3 and 10 of the Pittenweem and Anstruther 

 section. 



Myalina crassa, Flem., another gregarious species, is found with 



* This species is described from a patch of strata, isolated by volcanic ash, 

 near Ardross (Eev. T. Brown in Trans. Eoyal Soc. Edin. xxii. p. 392), the exact 

 stratigraphical position of which is not very clear. In the Geological Survey 

 Map, sheet 41, these beds are coloured as Carboniferous Limestone, which may 

 possibly be correct ; but Schizodus Salteri is not known from any other Car- 

 boniferous-Limestone locality, and the general character of the strata is as much 

 like the highest portion of the Calciferous Sandstone, as exposed to the east of 

 St. Monans, as any part of the overlying series that I have seen. 



