74 BRITISH PALALOZOIC FOSSILS. [Zooruyra. 
by close, delicate, irregular, vesicular plates; the most usual character of the Jamellz, both of the Eifel 
and Devonian specimens, is to be extremely thin and slightly flexuous near the outer wall, straight and 
much thickened in the middle half of their length, and again becoming thin and irregular, towards the 
spirally twisted inner ends; the secondary lamell being much thinner and about a third shorter than the 
primary; in other specimens (and parts of the same specimen) the primary and secondary lamellze are more 
nearly equal in length and thickness, and the fusiform section or mesial thickening of the lamellie not 
so obvious. 
A young specimen, eight lines in diameter, has sixty lamella. When weathered in a favourable manner 
the lamellee are seen to be perforated by central rows of tubes, parallel with their sides, extending from 
the outer wall to their inner edge, where they produce denticular perforated papillee, as in Mr Lonsdale’s 
supposed genus 7ryplasma. 
Position and Locality—Common in the Devonian limestone of Newton Bushel. 
Genus. PETRAIA (Miinst.) See p. 39. 
Perrata ceytica (Lam. Sp.) 
Syn. and Ref—Turbinolia celtica, id. Exp. Method. t. 78. f. 7 and 8. = Turbinolopsis, id. and T. pauciradiahs 
(Phill.) Pal. Foss. t. 1. f. 1 and 4. 
Sp. Ch.—Casts, obtusely conical, average length eight lines, and width (pressed flat) ten lines ; sulci 
left by the primary lamellz usually sixteen to twenty-two very strong, reaching nearly to the centre, the 
broad intervening ridges divided by an obtusely angular shallow sulcus, reaching two-thirds of the way from 
the edge of the cup to the base, in specimens of the above size, confined to the margin of the cup in 
specimens of smaller size, rarely forming a narrower obscure slit, representing the secondary lamelle ; the 
intervening obtuse ridges bear each a row of very small close elevated puncta, often obscurely marked, 
five or six in the space of one line. 
The specimen figured by Mr Lonsdale in the Memoir of Prof. Sedgwick and Sir R. Murchison, on 
Devonshire, as P. celtica, I find agrees most exactly in the obtuse sulci of the intermediary lamelle and 
other characters, with the 7. pauciradialis of Phillips, and I find no difference between those species, 
which I accordingly place together under the oldest specific name. The apparent great difference of the 
number of the lamelle in Prof. Phillips’s descriptions of the two species may be seen to arise from his 
counting all the Jamellze in one case and only the alternate or primary ones in the other. 
Position and Locality—Common in the carboniferous slate of Padstow *. 
PerratA Gicas (M°Coy). Fig. ¢, d, e, page 66. 
Ref—M Coy, Ann. and Mag. Nat. Hist. 2nd Series, Vol. IIT. p. 1. 
Sp. Ch.—Corallum elongate, conic, gradually increasing (at an angle from the apex, of about 30° ex- 
ternally) slightly oblique; section apparently elliptical, the axes in the proportion of 70 to 100; internal cast 
obtusely conic, expanding at an angle of about 50° in compressed specimens, its small end obtuse from the filling 
up of a considerable length of the base of the coral, by nearly solid sclerenchyme ; external walls thick, dense ; 
lamellee averaging seventy-four in the adult cups, with the diameter of two and half inches, the primary 
* A few localities noticed in the memoir of Prof. Sedgwick and Sir R. Murchison on the “Devonian System” 
struck me as so perfectly identical with the “Carboniferous slates’ of Dr Griffith, which in Ireland are developed 
near the base of the carboniferous system, that I asked and obtained Prof. Sedgwick’s sanction, on Paleontological 
grounds, to include them in the carboniferous period ; but as most people would look for the particular species in 
the Devonian sections of the present work, I have given them there, but calling the matrix Carboniferous Slate, to avoid 
mistake. I noted many years ago that many of the fossils from Tintagel, Padstow, &c. oceurred in the Irish ear- 
boniferous slates, and yet these certainly belong to the carboniferous, and not to the Devonian system, because in 
many places they are underlaid by carboniferous limestone containing numerous fossils, all of which I recognised as 
the ordinary forms of the great scar, or main Trish limestone. I have since recognised many of these Tintagel, We. 
fossils in great abundance in the undoubted carboniferous limestones of Derbyshire, &c.—I’. M°C. 
