198 
DESCRIPTION OF THE FOSSILS. 
tricts crinoidal fragments are not uncommon in particular parts of the 
shales, shaly gritstones, and cherts, small foraminated and reticulated 
corals also occur in them ; but the lamelliferous corals are almost wholly 
confined to the limestones. Several of the same species are common 
in the whole range of the formation, and, perhaps, if the local catalogues 
were more complete and more correct, it is probable that a very general 
conformity would be found to prevail in this respect. 
None of the zoophyta has yet been seen in the proper coal measures 
above millstone grit, a circumstance which, combined with the partial 
occurrence of them in the shales and grits below, and the almost universal 
abundance of them in the limestone group, appears to add a strong 
negative proof to the affirmative evidence of fluviatile genera of shells, 
of the fresh water deposition of most of the coal strata. 
POLYPARIA. 
Retepora. This genus occurs in the limestones, cherts, and shales 
from the beds alternating with old red sandstone to the upper millstone 
grit The openings in the net work are called fenestrules, the spaces 
between the ends of these dissepiments, those between the lines of fenes- 
trules interstices. In all the figures n signifies nat. size. 
R. membranacea. Ph. PI. I. fig. 1 to 6. Bolland ; Kildare County. 
Interstices straight, equidistant ; fenestrules elongated-oval ; dissepiments thick ; 
pores a little oblong, not prominent. 1 a conical specimen ; 2 its external face 
magnified ; 3 still farther magnified to shew the carinated interstices ; 4, 5 the re- 
verse granulated ; 6 cast of the reverse. 
R. flabellata. Ph. PI. I. fig. 7 to 10. Bolland; Harrogate; Rich- 
mond; Hawes; Middleham ; Kirby Lonsdale ; Brough; Kildare. 
Interstices straight, mostly equidistant ; fenestrules elongated, rectangular, equal ; 
dissepiments very thin ; pores small, prominent ; reverse of the interstices striated : 7 
small portion ; 8 the reverse striated ; 9 the obverse ; 10 interstices and prominent 
pores. 
R. flustriformis. Ph. PI. I. fig. 11, 12. Bolland; Harrogate; Rich- 
mond ; Florence Court, near Enniskillen. 
Fenestrules oval, in quincunx: I have not been able to see the obverse face. 
