114 R. Etheridge, jun.— Carboniferous Tubicolar Annelida. 
Sp. char.—Tube dextral, irregularly planorbiform, varying from 
1 mm. to 3‘5 mm. in diameter; volutions convex, 14 to 3, not all in 
the same plane, sometimes protruding on the attached side, so that 
more are visible on that than on the free side, but at other times 
flattened and even grooved; occasionally prolonged into a short 
free tube. The last volution either expands towards the aperture, 
when the latter has a somewhat sigmoidally curved margin, or it is 
sometimes prolonged into a short free tube, when the aperture is 
circular, and inclined a little to one side; general section of the tube 
circular ; umbilicus well marked, but not exposing more than the 
first two whorls or volutions of the tube. Surface sometimes nearly 
plain, but more usually ornamented with close, regular, direct, trans- 
verse microscopic stri# or ridges, which vary in their degree of 
strength, with occasionally one coarser and stronger than the 
others ; at times fine spiral striz are present. 
History.—In 1809 Mr. W. Martin described what he then took to 
be a small shell incrusting plant-remains preserved in an ironstone 
nodule from Chesterfield, under the name of Conch. (Helicites) 
pusillus,' and which he defined as a depressed, smooth, umbilicated, 
firmly-coiled shell, consisting of three round and tapering volutions, 
and with a subrotund aperture. From the general appearance of 
Martin’s figure, there can be little doubt that we have here the 
organism afterwards described by Murchison as Microconchus car- 
bonarius,” and first incidentally mentioned under this name as early 
as 1886 by the late Prof. J. Phillips,’ as occurring in the Ardwick 
limestone, near Manchester. 
The late Sir R. Murchison, in describing the fossil contents of a 
“freshwater limestone”? in the Shrewsbury Coal-field, proposed the 
name Micro. carbonarius for a “ very minute discoid univalve,” with- 
out any trace of chambers, and of which he gave figures of all the 
varieties noticed by him. This be it noted without any reference to 
Martin’s figure, of the existence of which he was probably un- 
acquainted. Murchison’s illustrations exhibit the various varieties 
of the M. carbonarius, both in the form of the mouth and surface 
ornamentation, and further that one of the specimens had been 
attached to some object smaller than itself, leaving a groove across 
one surface. On another page‘ Murchison quotes a letter from Prof. 
Phillips, who refers to the same little shell from the Manchester, 
Yorkshire, and Newcastle Coal-fields. He remarked that the volu- 
tions “touch one another like Planorbis when young, but when old 
are extended into a free tube as in Vermetus, or rather like Vermilia. 
The shell is sinistral like Planorbis, but sometimes shows proof of 
being attached on one side like Spirorbis. Lines of growth strong, 
somewhat irregular, deficient in parallelism, and oblique to the axis 
of the tube as in Planorbis; faint spiral strize can just be seen.” 
At the time Sir R. Murchison and Prof. Phillips were engaged on 
their investigations just referred to, Dr. Hibbert was conducting his 
examination of the Burdiehouse limestone, and he found therein 
* Petref. Derb. 1809, t. 52, f. 2 and 3. 2 Silurian Syst. 1839, p. 84, fig. D1-10. 
* Brit. Assoc. Rept. for 1836, pt. 2, p. 87. * loc. cit. p. 88. 
