G. W. Lee — Trepostomcita. 157 
Observations. —The presence of small interstitial cells, possibly of the nature of 
mesopores, suggests that this species is not a true Stenopora , but since it has not yet been 
observed from other horizons its true affinities cannot be established, and consequently it 
is here allocated to that genus for the sake of convenience only. 
The specimen from which the slide figured pi. xv, figs. 3, 4, was made is preserved 
in the collections of the Geological Survey in Scotland [M. 308 f ]. 
Stenopora uubia (M‘Coy). 
Plate XY, fig. 8. 
1844. Verticilloporu dubia M‘Coy. A Synopsis of the Characters of the Carbon¬ 
iferous Limestone Fossils of Ireland, p. 195, pi. xxvii, fig. 12. 
Description. —(a.) External characters. The holotype consists of a hollow branch 
bearing two offshoots. The main branch is cylindrical, 48 mm. in length and 6'5 mm. in 
width. It is split longitudinally and exposes the cast of the tube. The surface of the 
cast bears numerous oblique wrinkles, which show that the epizoarial membrane is 
wrinkled. The longitudinal fracture shows that the zooecia are, in their proximal portion, 
short and inclined at an angle of some 45 degrees to the surface of the epizoarial 
membrane. Their distal portion is 1 mm. long and at right angles to the surface. There 
are 40 zooecia along a distance of 1 cm. Very little of the surface is preserved. Where 
observable, the apertures are sub-polygonal, with narrow interspaces. The acanthopores 
appear to be of one kind only and are restricted to the junction-angles. 
Of the two offshoots, the lower one is at right angles to the main branch and 
approximately of the same size. Its distal end is hollow and flattened, but near its 
junction with the main branch it appears to be solid. The other offshoot, which is 
presumably the original of the enlarged figure given by M‘Coy, is a small dichotomous 
branch the apex of which points towards the proximal end of the main branch. Whether 
it really grew downwards is not clear ; it may be that it was partly displaced before 
fossilization took place. 
As seen on M‘Coy’s figure, the branching form is accompanied, in the same specimen, 
by an incrusting zoarium enveloping the shell of an Aclisinci. It is presumably an old 
zoarium, as its peripheral region attains a thickness of 1*5 mm., which is greater than in 
the holotype. 
(b.) Internal structure. A thin slice from the lower extremity of the holotype shows 
that the peripheral portion of the zooecia is closely tabulated. The thickening of the 
