CARBONIFEROUS BRACHIOPODA. 
275 
mens I have hitherto seen from Great Britain, France, or Belgium, and it appears to be 
a very far spread and common species. In a specimen of Sp. (glabra from the Carboni- 
ferous Limestone of Little Island, Cork, in the collection of Mr, A. Champernowne, the 
valves are closely covered by concentric lines, and in a similar manner as they occur in 
8p. incicrva, a Devonian form. I have not observed this feature in any other specimen. 
13. Spirifera lineatAj Martin, and var. imhricata, Sow. 
In Sup., PI. XXXII, figs. 6 to 11, I have given a series of figures showing important 
modifications in the shapes and directions of the spiral coils, from specimens admirably 
developed by the Rev. Norman Glass. The two specimens, figs. G, 7, are very remark- 
able, and belong to the variety imhricata. 
At page 225, and PI. LI, fig. 15, of my Carboniferous Monograph, I showed that the 
external surface of 820. lineata " was covered with numerous concentric ridges, rarely in 
any place more than a line apart, but usually very much closer, and from each of 
which projected numerous closely-packed [long, flattened, hair-like] spines, which 
thus formed a series of spiny fringes overlying each other all over the shell." 
Since then (in 1878) Mr. John Young, of the Hunterian Museum, Glasgow, has 
carefully examined the nature of these concentric rows of almost adpressed spines^ 
and has found that when these are viewed by the aid of a lens, or under the 
microscope in good light, they are transversely oval, with a faint longitudinal groove 
or depression along the middle (Sup., PI. XXXIV, fig. 9).^ He ascertained that 
when the spines are broken close to their root, or surface of the shell, two pits or pores, 
placed horizontally and close to each other, are observable in the interior of the spine, 
and that the spine is divided, to at least some considerable distance, if not its entire 
extent, by two circular or oval tubes, as in a double-barrelled gun (fig. 9 c, d). lie 
also noticed that tiiese double pits or pores do not pass through the thickness of the shell. 
These characters are clearly displayed in many well-preserved specimens from the 
Carboniferous Limestone Shale of Capelrig, East Kilbride, and Newfield, High Blantyre, 
in Scotland. 
Mr. Young has also examined the shell of a well preserved specimen from Brockley, 
near Lesmahagow, and this appeared to him to be minutely perforated, and the canals 
seem to pass through the thickness of the shell (?). It would, however, be desirable 
that this perforated character of the shell should be corroborated by further examination 
of well-prepared vertical sections. 
In a specimen from the Carboniferous Limestone of Cork, in Ireland, Mr. 
^ Mr. Young has recently discovered that these spines are provided with numerous marginal opposite 
booklets, usually pointing towards the free end of flattened spine. See, for further details and jSgure, 
explanation of Sup., PI. XXXIV, footnote and woodcut. 
36 
