177 
G. W. Lee — Trepostomata. 
Distribution. —The original of pi. xvi., figs. 16, 17, was collected by Mr. W. B. 
Wright, from the Upper Calp Shale of Bundoran, Ireland. This is the only locality 
in the British Isles at which a Carboniferous Batostomella has so far been found. 
Comparable species. —The arrangement of the tabula; and acanthopores shows some 
resemblance to that of the American Batostomella spinulosa Ulrich, which differs in having 
larger zooecia and a shorter peripheral region. 1 Longitudinal sections of B. bundorensis 
might, when the tabulae are not shown, easily be confounded with sections of certain of 
the species classed here as Dyscritella ; but the latter have angular mesopores, and 
tangential sections will show the difference. 
Genus Leioclema Ulrich. 2 
Leioclema avonense sp. nov. 
Plate XIV, figs. 14-16. 
Description. —(a.) External characters . In the specimens examined the zoarium is 
composed of solid cylindrical branches attaining a thickness of 22 mm. The apertures 
of the zooecia are separated by interspaces so thin that their outline is consequently 
polygonal ; some thirty occur along a distance of 1 cm. The mesopores are angular 
and rather irregularly distributed. The condition of the surface is such that the external 
characters of the acanthopores cannot be determined. It is also not possible to say 
whether maculae or monticules are present, but neither occurs in the small portion of 
surface available for study. 
( b .) Internal structure. The zocecia are longitudinal in the axial region. By a 
rather gentle turn they assume a radial direction, but without evincing any appreciable 
thickening of their walls, most of the inter-zooecial space being occupied by the mesopores. 
The tabulae are scarce and irregularly distributed in the zooecia. They are much more 
abundant in the mesopores, though not crowded, being generally more than their diameter 
apart. In both sets of tubes they are always complete, and much stouter than in the 
majority of the species of Trepostomata noticed in this contribution. 
Owing to the absence of a sharp change of direction in the course of the tubes, it is 
not possible to determine exactly the ratio of axial region to diameter. It probably 
oscillates between 05 : 1 and 0*6 :1. 
F 2 
22239 
1 42, pi. lxxv., fig. 1. 
2 A diagnosis of the genus is given on p, 151. 
