Rev. N. Glass—The Spirals of the Brachiopoda. 77 
they have their long axis at various angles, and are mostly small, 
except at Parn Voose, Cavouga, and Green Saddle. The felspathic and 
hornblendic lines often circle round the crystals. 
Such is a brief statement of the bare facts of our observations in 
this particular direction. Without discussing any theory as to the 
true nature and origin of the whole of the schists, we think that 
_ the porphyritic structure, so prevalent in the dark bands of the 
“ Granulitic Group,” in many of the micaceous and other rocks, as also 
in the later intrusions cutting the serpentine, indicates an igneous 
origin for many rocks hitherto regarded as schists. 
VI.—On tHe Prinorpat Mopirications oF THE SPIRALS IN THE 
Fosstn BracHIopopa. 
By the Rev. Norman Guass. 
R. DAVIDSON, assisted by the writer, gave a provisional sketch of 
the classification of the spiral-bearing Brachiopoda in the volume 
of the Paleontographical Society for 1883." As Dr. Davidson then 
said, our design was “to assist those paleontologists who might feel 
inclined to continue the subject.” The following notes have been 
written by me for the same end, and I think that if they are 
carefully read and compared with the figures in Dr. Davidson’s 
Carboniferous, Devonian, and Silurian Supplements, they will give 
a tolerably clear idea to the student of a very complex and difficult 
subject. I have perhaps some claim to write upon this subject from 
the years of close and continuous investigation which I have devoted 
to it, and from the fact that I have discovered a large proportion of 
what is now known concerning the spirals and their connections. 
In the “ Geologist,” 1858 (vol. i. pp. 457-473, folding plate xii.), 
Dr. Davidson gave figures and descriptions of all that was known up ~ 
to that date concerning the spirals and their connections. The com- 
parison between these figures and those given in his Carboniferous, 
Devonian, and Silurian Supplements in 1880 and 1882 is very 
remarkable as showing how recent have been the great majority of 
the discoveries in this interesting group. I have thought, therefore, 
that it might add to the interest of my notes if I gave in each case 
the date of the discovery and the name of the discoverer, that is, so 
far as these are known. Of course it will be understood that there 
are many genera and species which have the same internal characters 
as to the position of the spirals, their attachments to the hinge-plate, 
1 Anticipating a delay of fifteen months, owing to the retarded appearance of his 
Monograph in the Paleeontographical Volume, the veteran author on the brachiopoda, 
Dr. Davidson, published the result of his labours, in association with the Rey. 
Norman Glass, concerning the calcareous spirals of the Paleozoic Brachiopoda, in 
the Grotocicat Macazine for 1881 (Decade II. Vol. VIII. pp. 1, 100, 145, and 
289), illustrated by Plate V. and fourteen Woodcuts. It will be well for the reader 
to refer to these articles, as the figures therein given more fully elucidate the present 
paper, and the whole subject is treated in greater detail by Dr. Davidson; save and 
except the additional remarks made by Mr. Glass herein, which refer to discoveries of 
a later date than 1881.—Ep. Grou. Mae. 
