CARBONIFEROUS BRACHIOPODA. 
277 
Suh-genus Spiriferina, d'* Orbigny . 
15. Spiriferina laminosa, M'Coy, sp. Spirifera. Dav., Garb. Mon., p. 36, PI. VII, 
figs. 17—22. 
Spiriferina laminosa, King. A Monograph of Sp. cuspidata, Annals and Mag. of 
Nat. Hist., ser. 4, vol, ii, p. 11, &c., 1868. 
Since publishing my description of this species, Prof. W. King has stated in print 
that it occurs in various conditions of fossihsation, and that the best preserved examples 
were obtained from Redesdale, in Northumberland. " The fibres are well displayed, 
twisting about more or less, and separating or pushed aside by the intrusion of 
the perforations. [This character is also beautifully seen in the shell-structure of 
Spiriferina octoplicata, from Blantyre, Scotland. — J. Y.] In general, the perforations 
are well defined, so that their diameter, which is inch, can be tolerably well 
determined. They occur pretty regularly at about inch from one another, but 
occasionally a smaller perforation makes its appearance in the intermediate spaces." 
He likewise observes " that the histology of Spiriferina laminosa^ and the changes 
These two forms present us with several variations in shape, which in some cases seem to be peculiar to 
certain localities and to the strata of different geological horizons ; and as the species ranges from the Lower 
Limestones up to the Millstone-grit, the whole representing a group of strata some 3000 feet in vertical thick- 
ness, it is possible that some of the varieties may have been evolved from the earlier types, during the very 
long period of the accumulation of these strata. Although Sp. trUjonalis, with its variety bisulcata, are not 
known from any strata earlier than the Carboniferous period, yet it probably existed over some tract of 
the sea-bottom during pre-Carboniferous times. .... In the Lower Limestone Shales of the Beith 
district Sp. trigonalis on its first appearance presents us with at least three or four well-marked varieties, 
one of which has the fold more produced than any yet described (see Sup., PL XXXIV, fig. 2). This 
variety I have also found in the Upper Cement Limestone at Arden, near Thornliebank. One of the other 
varieties approaches closely to Sp. acuta, which has not yet been identified in Scotland ; the others agree 
with the typical varieties, Sp. trigonalis and Sp. bisulcata, although some of the latter are more transverse 
than are usually found. In the shales of Newfield, High Blantyre, a variety of Sp. trigonalis is found, 
which, in the extension of its hinge-area and elongated mesial fold, almost rivals tliat of Sp. triangularis, 
from which it is known by its more numerous ribs. This wide variety is there the only form of the species 
that has yet been found. 
" One of the largest and finest varieties of Sp. bisulcata obtained in the West of Scotland is that found 
in the shales overlying the Cement Limestone at Orchard, near Gilfnock, on the Busby Railway. The strata 
belong to the Upper Limestone series, and this form, so far as yet known, seems to be peculiar to that 
horizon. It is very deep between the valves, and comes very near to Sp. Mosqiiensis, a species not 
hitherto recognised from Scotland, being only distinguished from it by its fewer ribs ; Sup., PI. XXXIV, 
figs. 3, 4. It is very probable that all these varieties of Sp. trigonalis are only varieties produced by 
descent from one original type, which seems to have been very variable, the variations probably being 
caused by the condition of the sea bottom on which it lived." 
