EXPLANATION OF THE PLATES. 25 
Diplograpsus teretiusculus, Mr. Salter, in Journ. Geol. Soc., vol. viii., p. 329, 
pl. xxi., figs. 3,4. Mem. Geol. Surv., vol. iii., p. 330, pl. xi. a, fig. 3. 
a, b. From the original figures in the Journ. Geol. Soc., vol. viii., pl. xxxi.. 
fig. 3, a, b. 
a. MGitural size (uncompressed). 
b. Portion of do. enlarged four diameters, being the edge view, which shows 
the orifices of the cells. 
e, d, original. Uncompressed fragment, showing the arrangement of cells on 
each side of the axis; the lower portion, having been removed, has left its 
impression, in which the interior of the cells and their connexion with the 
central canal may be observed. From a specimen collected and presented 
by Professor Harkness to the Museum, Geological Survey of Ireland; from 
black slates, Upper Llandeilo, Little Queensberry Burn, Dumfriesshire ; 
other and well-preserved specimens in the same Museum were also collected 
by that gentleman from Glenkiln, Dumfries, in similar black shales. 
Lower LianpetLo.—Ty-obry. Upper LuanpEito.—Conway, Mona Mine, 
Anglesea; Llanerchymedd, &c., N. Wales; Pembrokeshire, S. Wales ; 
Mem. Geol. Surv., vol. iii., pp. 258, 330. Dumfriesshire, Prof. Harkness. 
In Ireland, at Lady Elizabeth’s Cove, Tramore, Co. Waterford, and Bally- 
money, near Gorey, Co. Wexford, W. H. B. 
Fic. 5.—a, b. DinymMocrarsus Murcuison®, Beck, sp. 
Graptolithus Murchisoni, Beck, Sil. Syst., p. 695, pl. xxvi., fig. 4. Clado- 
grapsus, Prof. Geinitz, Die Graptolithen, p. 30, pl. ii., fig. 40. 
a. Original. Fragment of dark grey slate, on which several examples of this 
double Graptolite are impressed ; some of them illustrate the remarkable 
effects of cleavage, which has separated and disturbed the relation of one part 
to another. Museum, Geol. Survey of Ireland, from Upper Llandeilo Flags, 
Abereiddy Bay, Pembrokeshire. 
b. Original. Enlarged four diameters: view of some of the cells, from well- 
preserved specimens collected by the Geol. Surv. of Ireland, near Duleek, 
county of Meath, described by the author in the Journ. Geol. Soc. of Dub- 
lin, p. 300, vol. ix., pl. iv., fig. 1d. 
LLANDEILO FLaGs.—Llandrindod Hill, Radnorshire ; Siluria, third edition, pl.i., 
“fig. 1 (description) ; Llanfair ; Welchpool; Abereiddy Bay, Pembrokeshire; 
Catal. Brit. Foss., p. 52 ;? Llandeilo, near Duleek, Co. Meath, W. H. B. 
Fig. 6.—a-d. DipDyMOGRAPSUS SEXTANS, Hail, sp. 
Graptolithus sextans, Hall, Paleontology of New York, vol. i., pl. Lxxiv., fig. 3. 
Cladograpsus, Prof. Geinitz, Die Grap. 1852. D. sextans, Salter, in Journ, 
Geol. Soc. 1848, vol. v., p. 17, pl. i. fig. 10, d, e. 
a. Original. A group of these remarkable little diverging Graptolites, well 
preserved in dark grey shale, collected by Mr. C. Galvan, of the Geological 
Survey of Ireland, at Dalligan Bridge, five miles N. E. of Dungarvan. 
b. Original. Enlarged portion of fig. 6 a, showing cell denticles. 
e. Original. Enlarged portion of fig. 6 a, showing double radicles at the 
base, from which the two branches diverge. 
d. Original. From a specimen in black fissile shale, collected and presented 
by Professor Harkness to the Geol. Surv. of Ireland, in which the double 
radicles and cell denticles are rather obscure : ‘‘ Graptolite shales” (Upper 
Llandeilo); Glenkiln, Dumfriesshire. 
E 
