630 KEPORT— 1891. 



Black Band, over Old Coal ; Anthracosia, Fish . Brackish 



Spotted Vein; Spirorbis; track of Limulus (?) 6 feet below 



the vein . Brackish 



Red Vein ; Anthracosia, Modiola, Edmondia (?) . Marine ? 



Blue or Big Vein ; Myalina, Anthracosia, Spirorbis Marine ? 



Bottom Veins ; Fish (8 genera) Brackish 



Kosser Veins (under the Farewell Rock and above the Mill- 

 stone Grit) ; Brachiopoda (7 genera), Conchifera(8 genera), 

 Gasteropoda, Heteropoda, and Cephalopoda (9 genera), 

 Encrinite Stems, Fish remains , Marine 



Anthracosia ' was originally regarded as Unio by Sowerby, then referred to 

 Cardinia by Agassiz, and to Pachyodon by Stutchbury ; but it was ultimately 

 defined by W. King as related to Unio, but, being distinct from that genus, it was 

 named by him Anthracosia. Mr. Salter noticed that it has a wrinkled epidermis, 

 and considered that it was related to the Myadce, and of brackish, if not marine, 

 habitat. This is the shell composing the so-called 'mussel bands' and 'Unio 

 bands ' of the Coal-measures. 



Anthracomya, ' Iron-ores,' &c., page 229. Mr. Salter indicates that the shells 

 which he describes under this name have oscillated in catalogues between Avicula, 

 Modiola, and Unio, and that it has a wrinkled epidermis, like the foregoing. 



Anthracoptera - is a triangular shell, "ndth wrinkled epidermis, and belonging 

 to the same group as the above. 



All the forms of this charactei-istic group of Coal-measure shells are called 

 Naiadites by Dawson,' and regarded by him as allied to D'Orbigny's Byssomwdonta. 

 Giimbel and Geinitz have described them as belonging to Unio and Anodon ; and 

 Ludwig refers Anthracoptera to Dreissena. At all events there is a great prob- 

 ability of their not being truly marine. They ma)^ have lived in the brackish vi'ater of 

 lagoons and creeks in the black, muddy swamps, having some communication with 

 the sea, and often or occasionally inundated with saltwater. (Dawson, Salter, &c.) 



Spirorbis carbo7iarius is frequent in the Coal-measures of South Wales and else- 

 where. This little annelid, though belonging to a marine geuus, is often found 

 attached to plant fragments in the coal-sbales. These plants may have hung down 

 into the water and been infested by the annelid ; or it may have attached itself to 

 floating plants which were ultimately drifted back to the littoral mud-swamp. 

 This Spirorbis is an important constituent in the Ardwlck limestone of Manchester 

 and Shropshire, but is associated with Ostracoda (Carbonia), which are probably 

 of brackish-water habitat. 



The Brachiopoda are necessarily marine. The lish are not good witnesses, for 

 they might have migrated to and fro, as some now inhabit both fresh and salt 

 waters ; and some might have been essentiallj' estuarine. 



Thus there are few decidedly marine beds in this series, and these, of course, 

 correspond with the occasional domination of the sea during its inroads and during 

 extreme depressions of the district. 



In addition to the occurrences of fossils in Salter's list above quoted we may 

 notice that in the ' Geol. Mag.,' 1870, pp. 214-220, is an account of some fossils 

 discovered by the late Mr. W. Adams, of Cardiff", in 1869, in a 'Black Band ' in 

 the Rhymney Valley, about 800 feet higher in the Coal-measures of South Wales 

 than any hitherto found. The band is calculated to have been rightly 81 feet above 

 the Mynyddysllwyn coal, from which it is divided by a fault ; it is in five layers, 

 and about 8 feet thick, with its associated shales. One of these in its midst and 

 the lowest shale carry the fossils. With some plant remains there is Anthracomya, 

 with Estheria (?) Adamsii, E. tenella, and Leaia Leidyi, all probably of brackish 

 habitats ; also Carbonia Evelincp- and C. Aynes, Ostracodes typical of a genus which 

 is found in the black shales, presumably of either fresh- or brackish-wat«r origin. 

 Mr. Adams also found a shale full of Anthracmnya at Aberbeeg, Ebbw Vale, over- 

 lying the Troed-rhiw-Clawdd coal, and 226 yards below the Mynyddysllwyn coal 

 (p. 215). 



' Iron- Orel South Wales, pp. 226, 227. ' Salter, Q.J.G.S., vol. xix., 1863, p. 80. 



• Acadian Geol, 1868, pp. 201-203. 



