46 BRITISH PALAZOZOIC FOSSILS. [Poryzoa. 
This coral seems to agree exactly with the American ones from the shaly beds of the Trenton lime- 
stone. I can find no trace of axis any more than Mr Hall. 
Position and Locality—Common in the shales of Llansantfraid, Glyn Ceiriog, Denbighshire ; appa- 
rently a dwarf variety (five cells in one line), % Var. minor, occurs in the schists, Llechwedd, Llwyd. 
Pritopictya (Stictopora) costELLATA (M‘Coy). Pl. 1. C. fig. 15. 
Ref.—M°Coy, Ann. Nat. Hist. 2nd Series, Vol. VI. p. 287. 
Sp. Ch.—Corallum frequently dichotomising at an acute angle ; average width about one and half lines; 
sides gently convex; section acutely elliptical; edges acute with a rather broad lateral margin, with a 
minutely granular non-celluliferous surface, each surface averaging from seven to ten rows of longitudinally 
oblong, or nearly oval cells, arranged in alternating longitudinal lines (six to eight rows in the space of 
one line, about four or five cells in the same space in each row) ; cells about a third longer than wide, and 
half their length between the rows, and about half their width between the cells of each row, giving the 
casts the appearance of being regularly marked with longitudinal sulci; intercellular spaces very minutely 
granulose. 
The suleated appearance of the cast and the linear arrangement of the cells easily distinguish 
this species from the Ptilodictya (Stictopora) acuta (Hall. Sp.) By grinding down a fragment I have 
ascertained with certainty, the presence of the flat internal axis, which is, however, of great delicacy, and 
not to be seen in the shale or sandstone specimens. 
Position and Locality—Not uncommon in the slates of Llansantfraid, Glyn Ceiriog, Denbighshire ; 
calcareous schists of Mathyrafal, S. of Meifod, Montgomeryshire ; and limestone of Girvan, Ayrshire. 
Explanation of Figures—P\. 1. C. fig. 15. Branch natural size, from the slates of Llansantfraid.— 
Fig. 15a. Section of ditto magnified eight diameters, shewing the thick flattened axis or plate on which 
the two rows of cells rest.—Fig. 154. Ditto. Portion of surface of cast magnified six diameters, shewing 
the granular non-celluliferous margin, and the linear disposition of the lengthened cells. 
Prinopictya (Séictopora) EXPLANATA (M‘Coy). Pl. 1. C. fig. 16. 
Ref —M Coy, Ann. Nat. Hist. 2nd Series, Vol. VI. p. 286. 
Sp. Ch.—Corallum forming large, funnel-shaped, foliaceous flexible expansions, upwards of three or four 
inches long, and upwards of two inches wide; axis semi-membranous, very thin, marked with small close 
concentric or forward-curved undulating wrinkles; tube-cells pyriform, oblique, three or four times longer 
than wide, narrowed posteriorly, anterior ends of the adjacent cells convex rhomboidal with a round per- 
foration nearest the anterior edge; cells separated by depressed lines which (when finely preserved) shew 
one or two alternating rows of small cellules; about seven or eight cells in a space of two lines. 
The broad foliaceous expansions of this species readily distinguish it from any of those described by Mr 
Hall, as well as the very narrow depressed spaces between the cells on the surface and the broad rhom- 
boidal, convex, portion of the cells surrounding the aperture. Finely preserved casts of the surface shew 
the strong granules on the ridges, corresponding to the intercellular depressions of the true surface. Old 
specimens often shew a few thick irregular branching ridges on the surface as in Newropora. One young 
specimen is flat and oval, like the base of Say’s Mavosites (Stenopora) Lycoperdon, with which it might 
be confounded if the posterior tapering of the cell-tubes was not noticed ; others are more elongate, conical, 
and the greater number of specimens are irregularly undulated films, parts of large expansions. The large 
expanded undulated and wrinkled axis, when the cells are rubbed off, resemble pieces of Stromatopora ; 
a careful search will however usually shew some remaining cells, or by rubbing through the thin axis, some 
of the cells of the under side will be brought into view, when their comparatively great size, and oblique 
ovate form will identify them. 
