262 R. Etheridge, jun Carboniferous Tubicolar Annelida. 
believe I am correct in considering Fig. 16 as the form which has 
been universally referred in Scotland to this species. 
Sp. caperatus frequently occurs attached to the surface of shells, 
but specimens have come under my observation without presenting 
any visible evidence of attachment. As originally figured, the tube 
terminated immediately following the second turn of the helix, but 
some time ago I pointed out that in many cases the shell was 
extended into a prolonged more or less curved free portion. I 
believe small granules can be detected on some specimens, studding 
the sharp transverse ridges; but on this point I cannot speak with 
certainty, as the specimens may have been deceptive. 
A close ally of this species is the S. Arkonensis, Nicholson,’ which 
has similar concentric ridges, and the mouth turned upwards. It is, 
however, both dextral and sinistral. 
Spirorbis laxus, Hall,’ is annulated and ends in a free tube like 
S. caperatus, but the annulations are more distinct, direct, and 
farther apart, judging from figures. 
Loc. and Horizon.—Occurs at many localities throughout the Scotch 
Carboniferous Limestone Series. Specimens before me are from 
Galabraes Quarry, near Bathgate; Roscobie Quarry, near Dunferm- 
line; Catcraig and Skateraw Quarries, near Dunbar ; the quarry at 
Carlops, Peebles-shire; all from shale connected with the Lower 
Limestones of the Carboniferous Limestone Series® (Ir. J. Bennie). 
5. Spirorbis spinosa, de Koninck. (Plate VII. Figs. 19-21.) 
Serpula spinosa, de Kon., Descrip. des Anim. Foss. p. 58, t. G. f. 8, a—e. 
»  Bronn, Index Pal. Nomen. 1849, p. 1139 (without description). 
Spirorbis ,,  Htheridge, Jun., Mem. Geol. Survey Scot. Expl. 23, p. 86 (7did). 
iy Armstrong and Young, Cat. W. Scot. Fos. 1876, p. 43 (27d). 
Serpula, et Spirorbis spinosa, Bigsby, Thes. Dev.-Carb. 1878, p. 243 (2bid). 
Sp. char.—Tube globose, forming a closed globular helix of from 
three to four whorls; back broad, its lateral margins more or less 
crenulate; umbilicus deep; section circular; surface covered with 
small, sharp prickles, or abortive spines, arranged in quincunx, and 
here and there a few transverse wrinkles. 
arity of S. spiosa in the Carboniferous rocks of 
Belgium is only equalled by its uncommon occurrence in those of 
Scotland. 
From 8S. caperatus, M‘Coy, to which it at first bears some resem- 
blance, the present species may be distinguished by the absence of 
the regular transverse ridges or rings of the former, a much broader 
back to the helix, and, so far as I know at present, the absence of 
the free terminal tube. If I am correct in stating that S. caperatus 
has small spines or prickles, a good point of similarity will be estab- 
lished, but not one sufficient for their union, because in S. spinosa 
the spines are scattered broadcast over the surface, whilst in S. 
caperatus, if they exist, they are confined to the crests of the 
annulations, and at the best only form a roughening of the latter. 
* Pal. Ontario, 1874, i. p. 121, f. 54, 6 and e. 
2 Pal. N. York, ill. p. 849; Atlas, t. "54, f. 18, a—e. 
3 For localities in the West ot Scetland, see Armstrong and Young’s ‘“ Catalogue,”’ 
and Mem. Geol. Survey Scotland, No. 23. 
