218 Mr. R. Etheridge and Dr. H. A. Nicholson ~ 
. 808; De Koninck, Nouv. Rech. Anim, Foss. Terr. Carb. Belgique, 
872, 1¢ pt.p. 157 (without description) ; Perceval, Geol. Mag. 1876, 
dec. 2, iil. p. 267, (cut) p. 268. 
Spec. char. Colony compressed, cuneate, longer than wide 
in the adult condition, more nearly pentagonal or hexagonal 
in the young state. Base more compressed than any other 
portion of the colony, sharp, but with rounded angles. Cups 
from two to five, but varying in number according to age, 
deep, conical, situated on the lateral margins and apex of the 
colony, and directed obliquely outwards and upwards ; those 
at the apex are round or oval, those on the lateral margins 
are more or less elliptical. The granular ridges on the inte- 
rior walls of the cups are slight and numerous. Perforations 
of the walls numerous and distinct. Surface marked with a 
multitude of fine, flexuous, broken, closely arranged, bifurcating 
vermicular ridges, directed obliquely inwards and downwards 
from the cup-mouths towards the base, where they become 
subparallel, and, from the presence of exceedingly minute and 
microscopic granules, assume a crenulate appearance. 
Obs. For the discovery of this, the type species of the 
genus, in British Carboniferous rocks, we are indebted to Mr. 
Spencer G. Perceval, of Henbury, near Bristol. We have 
examined examples of this species in which the cups have 
been as few as two and as many as five, with intermediate 
forms bearing three and four respectively. When in its 
youngest state the colony is decidedly of a more or less trian- 
gular outline (Pl. XII. figs. 11, 12), gradually assuming a 
pentagonal and perhaps hexagonal form; and it is not until 
there are at least four cups present that the typical elongated 
cuneate form is assumed. Both Milne-Edwards and Messrs. , 
Meek and Worthen mention the presence of two large “septa,” 
the former author stating them to occur in addition to the 
regular series of between thirty and forty smaller “ septa.” 
The examples of this species with which we have worked 
have not been in such a state of preservation as to permit us 
to distinguish these above the remains of the other granular 
ridges. P. cunetformis may be easily distinguished by its 
elongate compressed form (Pl. XII. figs. 9, 10), the lateral 
position of some of the cups, and its peculiar vermicular crenu- 
late surface. From P. cyclostoma it may be at once known 
by the entire absence of the very characteristic basal con- 
centric ridges of that species; and we are quite in accord 
with Von Seebach, Kunth, and De Koninck as to the identity 
of the P. cuneiformis of Haime and Edwards with the 
Sphenopoterium cuneatum, Meek and Worthen. 
Under the observations on the genus we have given some 
