DESCRIPTION OF PLATE XXII.
In all the figures the same parts are indicated by the same letters.
Fig. 1. Front view. Fig. 2. Oblique view of front and left side. Fig. 3. View of under surface. Fig. 4. Back view. Reduced.
ns. Anterior pillars of neural spine, thrown backwards, downwards, and towards the left by pressure.
ns'. Posterior pillars of neural spine.
vr. Vertical ridge, rough for attachment of an interspinous ligament.
prz. Praezygapophyses.
n. Interpraezygapophysial notch, =zygantrum.
z. The inner articular surface of the right praazygapophysis, forming one side of the notch.
w. The vertical wedge-plate descending from the junction of the postzygapophyses to the crown of the neural canal, which, when the vertebrae are articulated, is received into n, the notch between prz. It has been dislocated towards the left.
psz. Postzygapophyses.
np. Neurapophyses.
g. Groined interior arch.
nc. Neural canal.
fl. Its floor.
c. A small portion of the upper part of the centrum immediately under fl.
tr. Transverse process.
cs. Costal facet.
plt. Horizontal platform.
btt. Vertical buttress-plate descending from platform to centrum.
Discussion.
The President remarked on the combination of strength and lightness in the bone, which in this respect was not unlike the vertebrae of the back of the ostrich.
3. Note on the Middle Lias in the North-east of Ireland. By Ralph Tate, Esq., Assoc. Linn. Soc, F.G.S.
Portlock in his ' Survey of Londonderry ' makes no mention of the presence of the Middle Lias in Ireland ; and an examination of the species of fossils collected by him proves that no higher member of the Jurassic series than the Lower Lias is represented by them. In a former communication* I demonstrated the presence of the whole series of the Lower Lias, and, till recently, was unaware of the occurrence of strata newer than that formation.
Mr. William Gray has sent me several blocks of a grey, marly, micaceous sandstone, charged with organic remains of Middle Liassic age ; these were obtained near the town of Ballintoy, " in fields
faces exceeds the vertical (Owen) ; while in this Streptospondylus the reverse obtains, the vertical diameter of the best-preserved articular face (the hollow, posterior one) exceeds the transverse.
- Quart. Journ. Geol. Soc. vol. xxiii. p. 297 (1867).
