258 R. Etheridge, jun.—Carboniferous Tubicolar Annelida. 
TIJ.—A Conrrisution To THE Stupy oF THE British CARBONIFEROUS 
TusicoLaR ANNELIDA. 
By R. Erserives, Jun., F.G.S., F.R.P.S.Edin. 
(PLATE VII.) 
(Continued from p. 222.) 
ae following appear to be well-marked varieties of Microconchus 
pusillus. 
la.—Spirorbis (Micro.) pusillus, Martin, var. simplex, var. nov. 
(Plate VII. Fig. 8.) 
Var. char.—The coil of the tube is open, lax, and imperfect, repre- 
senting only a portion of the more developed coil; surface stria — 
very fine. 
Obs.—This variety bears a very close resemblance to a small 
Spirula. In all probability it represents the youngest stage of Sp. 
pusillus, and it is just possible that it may be identical with Golden- 
berg’s Sp. hamaius (Gyromices hamatus),' of the Saarbruck Coal-field, 
in which case, of course, his name would be adopted in preference to 
that now proposed. 
Loc. and Horizon.—Straiton Oil Shale Works, near Burdiehouse, in 
shale connected with the Burdiehouse Limestone. Cement-stone 
group, of the Calciferous Sandstone Series (I/r. J. Bennie). 
1b.—Sp. (Micro.) pusillus, Martin, var. Hibberti, Etheridge, jun. 
Nautilus, Hibbert, Trans. R. Soc. Edin. 1836, xiii. p. 151. 
»  Rhind, Excursions around Edinb. 1836, p. 35, f. 14e. 
Sp. carbonarius, Murch., var. Hibberti, Eth. jun., Quart. Journ. Geol. Soc. 1878, 
xxxiv._pt. 1, p. 3 (note), t. 1, f. 2. 
Var. char.—Size exceeding that of normal examples of the species 
itself, the last turn of the tube increasing more rapidly; aperture 
with a sigmoidal or nautiliform margin reflected somewhat back over 
the umbilicus, which is deep. By following the direction of the 
surface-striz, the sigmoidal margin can be traced. 
Obs.—Dr. Hibbert figured in his paper, “On the Freshwater 
Limestone of Burdiehouse, etc.,” published in 1836, a little shell-like 
body which he compared to a Nautilus, but noticed its want of septa. 
I have observed a similar in several shales at about the horizon of 
the Burdiehouse beds associated with Microconchus pusillus, but 
always to be distinguished from it by its larger size and regularly 
sigmoidal aperture. They may be only large crushed examples of 
the typical form of the species, although I hardly think this; at any 
rate they are far too common to be passed over in silence. I there- 
fore proposed for them some time ago the varietal name Hibberii. 
Loc. and Horizon.—Similar to the last (Mr. J. Bennie). 
; Section, Spirorbis, Lamarck. 
2.—Spirorbis ambiguus, Fleming. (Plate VII. Figs. 9-11.) 
S. ambiguus, Fleming, Edinb. Phil. Journ. 1825, xii. p. 246, t. 9, f. 3. 
be Bronn, Index Pal. Nomen. 1848, p. 1185. 
yy Etheridge, jun., Grou. Mac. 1877, IV. p. 318. 
Sp. char.—Tube globose, dextral, whorls one, to one and a half, 
* Fauna Sarepontana Foss. 1877, heft 2, p. 7, t. 2, f. 34, @ and 8. 
