548 
PROFESSOR OWEN ON SOME REMAINS OF THE 
the front border thins off almost to an edge. This border was received by the hind 
one of the segment in advance ; the hind border, though somewhat mutilated, fits 
very fairly the front border of the foremost of the coalesced segments ; in its present 
state it is, in great part, formed by the hind borders of the bases of the two pairs of 
solid conical processes. 
Of these the upper or dorsal pair (Plate 65, figs. 1-4, a, a) are the largest and 
longest; the transverse diameter of the base of each is 4 inches ; the antero-posterior 
diameter is 3§ inches ; the height, taken from the outer border of the base of the cone, 
is 4 inches. The body of the cone is subtrihedral with the apex directed obliquely 
upward, outward, and backward. The medial and hinder facets are convex both 
across and lengthwise ; the antero-external facet is partly flattened across and is 
concave lengthwise. The surface of this horn-core is roughened by numerous small 
neuro-vascular foramina, like those upon the cephalic weapons, indicative of the 
activity of the sheath-forming periosteum. The second pair, or lateral cores (ib., ib., 
b, b) are much smaller, and are mammilloid in shape. Each measures 2-g- inches across 
the base and rises to the same height, measured along the outer basal border. The 
hind border of the ring, as here conserved, is continued directly upon the base of the 
core ; the extension thereto from the fore border is more gradual. From tip to tip of 
the dorsal cores (a, a) is 10 inches; the same admeasurement of the lateral pair ( b , b) 
gives 9 inches. 
The cavity of the readjusted portions of the free caudal dermosteal girdle con¬ 
tained no corresponding endo-skeletal segment, nor any adherent parts of such. The 
vertebra had probably escaped the research of my friend. 
The anterior aperture of the antepenultimate coalesced segment exposed the 
corresponding caudal vertebra (Plate 64). 
The key-stone ridge, answering to that noted in the foregoing segment, was here 
confluent with the neural spine (ns.) of its vertebra; a like confluence attached the 
haemal spine (hs.) to the floor. Thus the area of the girdle was bisected by the 
vertebra. But the presence of a ridge ( e , e) from each side of the inner surface of the 
girdle, and the fractured ends of answerable transverse processes (cl, cl) directed thereto, 
indicated that the surrounding wall had been strengthened by both transverse and 
vertical buttresses. The centrum of this caudal vertebra is compressed and is directly 
continued, by coalescence, with the bases of both neur- and haem-apophyses. The 
centrum contracts to both these junctions, and narrows transversely to its exposed 
anterior part, the broken surface of which indicates bony union with a caudal vertebra 
in advance. The neural canal (to) has a transverse diameter of 5 lines, the vertical 
diameter is less : a low ridge projects from the floor of the canal. The section of the 
haemal canal (p) gives a vertical ellipse 3 lines by 1^ lines. 
The inner surface of the bony girdle is moderately smooth, as in the anterior segment: 
the outer surface differs chiefly in the larger size of the lateral horn-cores (//). The 
upper or dorsal pair (Plate 64, a) present the same size as in the free segment, with 
