On applying a fragment of the back of a vertebra in Mr. Fox's collection (woodcut), we found that when the postzygapophyses rested on the praezygapophyses, the posterior vertical median plate fitted into the notch between the latter, its sides articulating with the subtriangular articular surfaces of these.
Fig. 1. — Reduced outline of a camera-drawing of a fragment of the back of a similar vertebra in Mr. Fox's collection.
ns'. Posterior pillars of composite neural spine.
psz. Postzygapophyses.
w. Vertical median wedge-plate descending from junction of psz to crown of neural canal.
vr. Vertical mesial ridge, for interspinous ligament.
vp. Thin vertical plate descending to platform.
plt. Horizontal platform.
The neural spine consists of an anterior pair of pillars (now about 7 inches long) which rise from the crown of the neural arch immediately behind the praezygapophyses (ns), and of a posterior pair of stouter pillars (ns) which ascend from immediately above the postzygapophyses. The two front and the two posterior pillars are joined by a thin lamina ; and other thin plates pass between the front and back pair. The plate which unites the two front pillars is indented ; so that these pillars are separated by a deep retiring angle, open forwards ; while the plate which connects the two posterior pillars developes a vertical median crest (vr) projecting backwards, and having a strong, rough edge, as if for the attachment of an interspinous ligament. Below, the crest contracts, and ends in a deep hollow just above the union of the inner borders of the postzygapophyses.
