Zoorpuyra.]| LOWER PALAZOZOIC RADIATA. 33 
Genus. CLISIOPHYLLUM (Dana). 
Etym.—kNiowy, a tent (from the conical central boss). 
Gen. Char.—Corallum simple, branched, or aggregate, with vertical radiating lamelle ; a thin epitheca 
or outer wall: internal structure (vertical section), central area composed of small vesicular plates and 
cells converging or arching upwards to the centre, so as to form a conical boss in the cup; no distinct 
central axis; outer area of small cellular structure, inclining in the opposite direction or upwards and 
outwards, separation between these areze formed by an intermediate area of larger, nearly horizontal, 
cellular structure ; (horizontal section) a large central area of small irregular cellular texture, from which 
the primary lamelle radiate to the outer walls, intermediate zone with few vesicular plates between the 
lamellze ; outer zone haying the primary and secondary lamellze connected by very numerous vesicular plates. 
The upward wave of the vesicular plates in the middle area of the vertical section, and consequent 
projecting boss in the middle of the cup, separate this genus from some of the radiated Cystiphylla. 
CLISIOPHYLLUM VORTEX (J/°Coy). PI. 1. B. fig. 18. 
Ref—M°Coy, Ann. Nat. Hist. 2nd Series, Vol. VI. p. 277. 
Sp. Ch.—Corallum simple, conic, slightly curved, enlarging at the rate of one inch eight lines in three 
inches from the apex; outer wall thin, faintly marked with subequal longitudinal lamellar strie (five or 
six in the space of three lines at a diameter of one inch), and small concentric wrinkles; at a diameter 
of one inch the horizontal section shews an outer area of about sixty thick, equal, radiating lamelle, 
barely reaching one-fourth of the diameter towards the centre, connected by small irregular transverse 
vesicular plates; a few of the pairs have a very thin, short, marginal lamella between each of the larger 
pairs, and where this occurs the vesicular transverse plates become much more numerous; inner area 
rather more than half the diameter, forming a circular mass of confused vesicular tissue, crossed by a few 
arched radiating delicate lamellee: vertical section, having the narrow outer area on each side (corresponding 
to the lamelliferous zone) of arched vesicular plates, forming large unequal horizontal or slightly inclined cells, 
one or two cells extending across the width of the area; wide inner area composed of small oval cells 
arranged in much-curved transverse rows, the convexity of the curve upwards. 
Position and Locality—Wenlock limestone, Wenlock, Shropshire. 
Explanation of Figures—Plate 1. B. fig. 18. Natural size from Wenlock.—Fig. 18a. Do. Vertical 
and horizontal sections near base, natural size, shewing the very large vesicular inner area of rows of 
upward-curved cells, the narrow outer area containing the primary radiating lamelle in the horizontal 
section, and large vesicular tissue in the vertical section; and the extremely narrow layer of minute 
vesicular tissue lining the wall and corresponding to the short secondary lamelle in the horizontal 
section. 
3rd Subfamily. NEMATOPHYLLIN &. 
Corallum rarely simple and turbinate, usually compound, of numerous polygonal tubes; in either case 
each cell defined, by a distinct, solid, outer wall or epitheca, within which is a vesicular outer or perithecal 
area, either radiated or not, by the costal extensions of the lamellz; within this outer zone is an inner 
cylindrical area, forming the true cell-tube, defined by a thin wall and containing the radiating lamelle, of 
two sizes, connected by numerous transverse vesicular plates; usually a distinct central axis. 
The corals of this subfamily are distinguished by the perithecal zone round the cell-tubes, defined for 
each individual by a solid boundary wall or epitheca, sometimes single, sometimes double in the massive 
species. 
Genera :—1, Nematophyllum ; 2, Stylaxis ; 8, Strombodes ; 4, Lonsdaleia ; 5, Stylastrea; 6, Acervularia ; 
7, Siphonodendron. 
F 
