76 BRITISH PALAZOZOIC FOSSILS. [Poryzoa. 
FENESTELLA PLEBEIA (J/°Coy). 
Ref—M°Ooy, Carb. Foss. Irel. t. 29. f. 3. 
Sp. Ch.—F lat, expanded, fan-shaped ; interstices thick, carinated ; fenestrules equal, rectangular, from two 
to three times as long as wide; width equal to that of the interstices; dissepiments thin, regular; pores 
four or five to the length of a fenestrule, with slightly prominent margins, about their diameter apart ; 
reverse, minutely granulated, and very coarsely sulcated longitudinally ; nearly four fenestrules in the space 
of two lines measured longitudinally, six to seven in the same place measured transversely. 
This is a very abundant species in the carboniferous limestone series, and one of the two species con- 
founded under the name Fenestella antiqua, by Mr Lonsdale and Prof. Phillips, in the carboniferous slates 
of Petherwin, seems to be only a slightly more slender variety. 
Position and Locality.—Of the last-mentioned variety, abundant in the Carboniferous Slate* of Petherwin. 
For the localities of the other varieties, see the section on the Zoophytes of the Upper Paleozoic Rocks. 
FENESTELLA PRISCA (Gold. Sp.) 
Syn. and Ref—Retepora prisca Gold. Pet. Germ. t. 36. f. 19. (not Frenestella prisca Lonsd. Sil. Syst.) 
Sp. Ch.—Corallum forming broad, undulating, fan-shaped expansions, usually about two inches high ; 
fenestrules broad, ovate, or very obscurely hexagonal, alternately placed on most parts of the coral, two in 
two lines measured vertically, three in the same space measured across ; interstices about half the width 
of the fenestrules near the margins, about two-thirds the width near the base; dissepiments about as wide 
as the interstices; surface of reverse marked with close flexuous, longitudinal striz. 
I have noticed distinct traces of a wrinkled, membranaceous covering, filling up the fenestrules in several 
eases, giving strength to a suggestion T threw out in my volume on the “Limestone Fossils of Ireland,” 
that all Fvnestella, when perfect, probably had such a covering as we see strongly calcified in Hemitrypa. 
The specimens I have examined do not shew the poriferous face, but there cannot, even from the above 
characters, be a doubt of its distinctness from the Silurian coral, which Mr Lonsdale has assigned to the 
same species. In Goldfuss’s figure the interstices are carinated, flexuous, with about four pores to the 
length of an interstice, and two to the width of a dissepiment. 
Position and Locality—Devonian limestone of Plymouth. 
6th Class) ECHINODERMATA. See page 51. 
Ist Ord. CrinorpEa. See page 52. 
Genus. CYATHOCRINUS. (Mill.) restricted by Aust. 
Gen. Char.—Oolumn round or pentagonal, with auxiliary side-arms ; alimentary canal round, or penta- 
gonal; cup composed of pelvis, Ist primary radials, Ist secondary radials, and one Ist interradial ; pelvis pen- 
tagonal, of five equal pentagonal pieces, alternating above which are four pentagonal and one hexagonal 
Ist primary radials (1st costals), alternating above the re-entering angles of which are five pentagonal 
Ist secondary radials (scapule), each with a small excavation in the middle of its upper edge for the 2nd 
secondary radial (1st arm-joint), which is much narrower than the preceding (or scapular) joint; the 
hexagonal Ist primary radial (or costal), supports on its upper truncated edge a large hexagonal Ist 
interradial (interscapular) plate. 
* See note at page 74. 
