218 Rk. Etheridge, jun.— Carboniferous Tubicolar Annelida. 
Breakwater, on the shores of the Firth of Forth, and soon. But 
the important point of all is, that at Woodhall, in company with such 
| forms as Discina nitida, Phill. Serpulites carbonarius, M‘Coy, 
a Chetetes, Lingula mytiloides, Sow., Bellerophon decussatus, Flem., 
a Murchisonia, a Pleurotomaria, a Conularia, remains of Orthoceras, 
and numerous bivalves, we have our little Wicroconchus carbonarius. 
In other words, I believe we have in this worm, a form which, 
although of marine affinity, was able to maintain life in waters 
very slightly removed from fluviatile; and that immediately on 
slightly marine influences manifesting themselves, from physical 
causes, in lagoons, swamps, or brackish-water arms of the sea, in 
which certain portions of the Carboniferous strata were in course 
of deposition, Iicroconchus was one of the first to establish itself. 
That Iam not alone in considering Microconchus as of brackish- 
water habit, the following extract from one of Lyell’s works will show: 
—‘‘In the Coal-fields both of Hurope and America the association of 
fresh, brackish-water, and marine strata with coal-seams of terrestrial 
origin is frequently recognized. Thus, for example, a deposit near 
Shrewsbury, probably formed in brackish water, has been described 
by Sir R. Murchison as the youngest member of the Coal-measures 
of that district. . . . The characteristic fossils are a small bivalve, 
having the form of a Cyclas or Cyrena, also a small entomostracan, 
Leperditia inflata, and the small shell of a minute tubicolar annelid 
of an extinct genus called Microconchus, allied to Spirorbis.”} 
The following passage clearly shows that in Mr. Salter’s mind 
some doubt existed as to the exclusively marine character of Spirorbis. 
‘“‘ At present all Spirorbes are marine, or, at the least, estuary shells, 
and their frequent attachment to stems of Sigillaria, and other coal 
plants, is a strong indication of the habitat of the plants themselves.’ 
In his able paper “On the Origin of Coal,” Mr. E. W. Binney 
strenuously supports the marine origin of that mineral, as opposed to 
the exclusively freshwater, or swamp theory of its accumulation. 
He says,’ “In a former paper ... I have stated that the Coal- 
measures have presented some appearance of having been deposited 
in an estuary; but further observations, and the great superficial 
extent of the formation, now lead me to believe that they must be 
considered more of a marine character, and that the currents which 
brought the débris did not altogether proceed from the river running 
into the sea, or by tidal action, but were chiefly produced by the 
subsidence of the bottom of the ocean itself. The occurrence of the 
Cypris and the Unio in the Upper Coal-measures has been considered 
indicative of the freshwater origin of those strata; but when these 
fossils are found in company with remains of the Iegalichthys, 
Holoptychius, Ccelacanthus, Ptatysomus, Paleoniscus, and other 
genera heretofore considered as of decidedly marine origin, their 
diagnostic value ceases, even if all of these genera were confined to 
fresh water; but it is well known that such is not the case, but that 
* Student’s Elements Geol. 1874, pp. 395-96. 
2 Tron Ores Gt. Brit. pt. 3, p. 227. 
° Mem. Lit. and Phil. Soc. Manchester, 2nd ser. viii. pp. 148-194. 4p. 184. 
