220 R. Etheridge, jun.—Carboniferous Tubicolar Annelida. 
dextral, or sinistral, according to whichever surface of the leaf to 
which they are attached is held up, the remains of these Carboni- 
ferous plants at times being so thin as compared with the solid shell 
of the Microconchus, that the latter is visible through it. I am able to 
confirm Dr. Dawson’s statement from an examination of specimens 
of Sphenopteris afinis, L. and H., to which the worm tubes were 
adhering on both sides. 
Many examples of Microconchus pusillus, when clear of matrix, 
really appear as if free, and unattached ; this, however, results from 
the smallness of the surface by which adherence took place. When 
fixed by the whole of one surface, that face of the tube is quite flat 
(Pl. VII. Fig. 2) ; but when adhering only by a portion of the attach- 
ment-surface, the inner whorls of the coil more or less protrude 
(Pl. VIL. Fig. 5), and are, to a certain extent, piled; or, in other 
words, as Messrs. Van Beneden and Coemans say of their Paleorbis, 
the attached side then shows more whorls than the other. 
Usually, at any rate in the typical form, the circular mouth of the 
tube ends off short ; if however perfect specimens are luckily obtained, 
the tube will be found to extend itself as a short free termination, 
and is sometimes directed more or less to one side (PI. VII. Fig. 9). 
The size of the tube of this species varies greatly. I have observed 
it varying between that of a pin’s head and a diameter of 3°5 mm. in 
an ironstone from Tamworth. 
If I understand Dr. Geinitz’s description of Gyromices correctly, it 
is said to be chambered. The expression he uses is “ mehrkammeri- 
gem Perithecium,”! a many-chambered Perithecium. Substitute 
tube, or shell, for “ Perithecium,” consequent on the non-fungoid 
nature of Gyromices, and we have it described as a many-chambered 
shell. This our WM. pusillus—which I believe to be identical with G. 
ammonis—is not. It may be that J do not comprehend the word 
“mehrkammerigem ” correctly used as itis here in a botanical sense, 
but in the ordinary acceptance of the term it would define the tube 
of Gyromices as divided into several chambers by partitions or septa. 
I have satisfied myself by means of sections taken in the plane of 
the coil that J pusillus is non-septate, bearing out, in this respect, 
the statement made by Van Beneden and Coemans that their 
Paleorbis is unprovided with any diaphragms. 
The abundance of this little worm in certain localities is almost 
incredible, whole beds of limestone being almost composed of its 
remains. Some idea may be formed of its plentitude by Mr. J. 
Young’s statement that he had counted on a single plant from the 
Airdrie Coal-field no less than three hundred individual tubes 
adhering to it.” 
Under the name Microconchus pusillus, Martin. I have united in the 
foregoing synonymy the British JZ. carbonarius, Murch., the American 
Spirorbis carbonarius, Dawson, the German Gyromices ammonis, 
Gopp., and the Belgian Paleorbis ammonis, VY. Ben. and Coemans. 
This may not be acceptable to all paleontologists ; but I have done 
1 Verstein. Steinkohlenformation in Sachsen, 1855, p. 3. 
* Proc. Nat. Hist. Soc. Glasgow, 1868, i. pt. i. p. 102. 
