OF THE COUNTIES OF NORTHUMBERLAND AND DURHAM. 263 
Coral conical or funnel shaped ; branches frequently 
bifurcated, compressed ; cells numerous, arranged in ob- 
lique irregular rows across the branches, an elevated ridge 
or cup-like margin round each cell ; transverse branches 
always cellular, very oblique ; reverse smooth or slightly 
furrowed longitudinally. 
In Magnesian-limestone ; common. Tunstall, Humbleton, 
Silksworth, Dalton--le-dale. 
This is another common and characteristic species of the lime- 
stone ; it often occurs of a great size. The branches are very 
irregular in breadth and thickness, and are scarcely ever in the 
same plane. The pores are more numerous and more irregularly 
arranged in this species than in any other belonging to the lime- 
stone of this neighbourhood. A characteristic figure of this 
species is given in the Geological Transactions. 
6. F. retrrormis, Schloth. 
Fenestella retiformis, Lons., Geol. Russ., 1., App. A, p. 631. 
Gorgonia infundibuliformis, Gold. Petrif. Tab. 36, f. 2, b. ¢. 
In Magnesian-limestone ; not common. Tunstall. 
The coral which we refer with some doubt to this species, 
somewhat resembles the F. virgulacea in its appearance, but the 
branches and cells are more regular, and the former less com- 
pressed. 
40. RETEPORA, Lamarck. 
1. R. Lonspaty, n. s. 
Coral narrow funnel shaped in its young state, folded 
into several compressed tubes in full grown individuals ; 
meshes, oval, numerous, arranged in quincunx ; cells, on 
the outer surface, tubular, not curved over each other, but 
piled horizontaliy, and arranged in two irregular rows 
along the interstices ; interstices narrow ; reverse inter- 
nal, smooth. 
In Magnesian-limestone; rare. Silksworth, near Sunder- 
land ; Tunstall-hill—M~. G. Tate. ; 
This is the only species of Retepora that we are acquainted 
with in which the cells are placed on the outside of the coral, 
