110 R. Etheridge, jun.—Carboniferous Tubicolar Annelida. 
The material upon which the following remarks are based com- 
prises a cellection from the Carboniferous rocks of Scotland, for the 
loan of which I am indebted to the kindness of Prof. A. Geikie, 
LL.D., F.R.S., the specimens contained in the Museum of Practical 
Geology, those of the British Museum, and a few kindly contributed 
by various collectors. The specimens in the Survey Cabinets, both 
of Edinburgh and London, are the result of collections made by Messrs. 
J. Bennie, A. Macconochie, and the late Mr. R. Gibbs. 
I am particularly indebted to my friend Mr. Bennie, who has 
done his utmost in every way to gather facts and specimens from all 
quarters, and has aided me with many valuable suggestions. I have 
also to thank Mr. EH. W. Binney, F.R.S., who some years ago permitted 
me to examine his collection of Spirorbis. 
The result of numerous observations in the field has shown that 
our Carboniferous Annelides, so far as habit is concerned, place 
themselves under three headings or conditions, viz. : 
a. Those leading a solitary life attached to Mollusca, Corals, 
Polyzoa, and other submarine objects—types Spirorbis caperatus, 
M‘Coy ; Ortonia carbonaria, Young. 
b. Those occurring in small clusters of individuals, too many in 
contiguity with one another to be termed solitary, but not in 
sufficient quantity to constitute a rock-mass—types Serpulites 
carbonarius, M‘Coy ; and frequently Spirorbis pusillus, Martin. 
ce. Those forming rock-masses, 7.e. occurring in such quantity that 
their shells or tubes after fossilization give rise to the formation of 
bands of limestone and other rock, often many feet in thickness— 
type Spirorbis helicteres, Salter. 
The following table shows the distribution of the British Carbon- 
iferous species according to the above results :— 
a. Solitary species. 
Spirorbis ambiguus, Flem. Spirorbis pusillus, Martin. 
»  Archimedis, de Kon. » _Sptnosa, de Kon. 
»,  <Armstrongi, Eth. jun. Serpula indistincta, Flem. 
»,  ecaperatus, M:Coy. Ortonia carbonaria, Young. 
»,  Dawsoni, Eth. jun. Ditrupa Ryckholti, Eth. jun. 
> Lichwald, ,, Vermilia, sp. 
(,,  globosus, M‘Coy.) 0 minuta, Bronn. 
»  wumtermedius, M‘Coy. ‘ 
b. Gregarious, or in clusters. 
Spirorbis pusillus, Martin (in part), Serpulites membranaceus, M Coy. 
Serpula Vorbanensis, Kth. jun. Sabella antiqua, M‘Coy, 
Serpulites carbonarius, M‘Coy. 
c. Forming rock-masses. 
Spirorbis helicteres, Salter. | Spirorbis pusillus, Martin (in part). 
Genus I.—Spirorbis, Lamarck, 1818. 
(Hist. des Anim. sans Vertébres, vol. v. p. 858. ) 
Section J/icroconchus, Murchison, 1839. 
(Compare Spiroglyphus, Daudin, 1800.) 
Microconchus, Murch., Sil. System, 1889, p. 84. 
Nautilus, Hibbert, Trans. R. Soc. Edin. 1886, xiii. p. 151. 
Spirorbis, Binney, Mem. Manchester Lit. and Phil. Soc. 1852, x. p. 196. 
