LINGULIDA. a7 
The shell is usually found in the state of cast, so that the surface-markings of the shell are 
not always sharply visible.” (It is, however, often perfect.—J. W. S.) 
Position and Locality. Of all the fossils found in the Lingula-flags this appears to be 
the most abundant, and especially so in the lower and middle portions, being quite rare 
in the upper part; but, as observed by Mr. Salter, it occurs of nearly full size again in the 
sandy beds of the Upper Tremadoc slate. Indeed, the designation of Lingula-flags was 
first applied (by Professor Sedgwick) in consequence of Mr. Davis’ discovery of Z. Davisi 
in these rocks near Tremadoc in 1845, for this shell was found to be so characteristic 
that it gave the name to the formation. It is, indeed, one of the oldest Brachiopoda 
hitherto discovered; but Mr. Salter informs me that other species of Zingula or 
Lingulella occur even 4000 feet lower down in the rock-series. 
In the appendix to Prof. Ramsay’s memoir Mr. Salter gives the following localities : 
Lower Lingula-flags (North Wales)—Carnedd Filiast, Bangor; Marchllyn-mawr, 
Llanberis; Tremadoc; Ffestiniog; Dolgelly; everywhere in the middle band of the 
Lingula-flags, rare in the lower black slates, at Maentwrog. In the Survey Collection 
there are many specimens from the Lower Lingula-flags of Pen-y-Bryn, five miles north 
of Dolgelly, Bryn-mawr House, &. ; near Nant-y-Groes, to the west of Bala, North Wales, 
and other localities. In South Wales—Whitesand Bay, near St. David’s Head, Pembroke- 
shire.. Abundant in the Upper ‘T'remadoc beds, at Deudraeth ; Garth. Prof. M‘Coy states 
that it is extremely abundant in the Lingula-slates south of Penmorfa; Tremadoc, 
North Wales; and he also quotes it from the Bala limestone of Coniston, Lancashire ; 
but from these Bala schists and limestones I have not seen specimens, and Mr. Salter 
tells me it is the true Z. ovata that is meant. And as I have already had occasion to 
observe, in the description of Z. ovata, I consider the specimen so named and figured 
by M‘Coy (‘ Br. Pal. Fos.,’ pl. 1 1, fig. 6), “from the Lingula-slates of Penmorfa,” to be 
only an elongated specimen of £. Davisi, and so shaped from the effects of cleavage. 
It occurs of every possible form. 
1 Mr. Salter observes, at p. 249 of his Appendix, that the range and persistence of this Lingulella 
(or Lingula) is remarkable ; it is found in quantity everywhere throughout the Tremadoc country and the 
vale of Ffestiniog, and through the wild moory ground as far east as Llyn Dywarchen, where it was 
detected by Prof. Ramsay. Mr. Salter found it there in plenty in 1853, and also at Pont Nant-y-Lladron, 
on the Bala road. Last of that line the hard Lingula-flags do not occur; but, followed to the south-west 
and south, it has been found by the Surveyors everywhere to hold the same horizon, that is to say, in the 
middle or quartzose series of the Lingula-flags. He has found it near the base of the slates, in company 
with Trilobites, near the Maentwrog waterfall, as above noticed; but it was small and ill-developed there, 
as it is also in the beds which overlie the Lingula-beds; yet, strange to say, it reappears in the upper 
portions of the next or overlying formation, of nearly its full size and character. We must also refer the 
reader to a very interesting paper by Mr. Salter, “On the Lowest Fossiliferous Beds of North Wales,” 
published in the ‘Report of the British Association for the Advancement of Science’ for 1852 (Transact 
Sections), wherein the author gives many details with reference to the geological position of the beds which 
contain Lingula Davisii, and which were, even at that time, determined by M. Barrande to be equivalents 
of his Bohemian “ Etage C.”’ 
8 
