206 Dr. C. W. Andrews—An Ichthyosaur from Peterborough. 
are well ossified with sharply defined edges. The neural arches seem 
to have persisted to the extreme end of the tail, and there may have 
been very small chevrons also. 
The neural arches of some of the anterior cervical vertebre consist 
of two lateral pieces, and in this case the anterior and posterior 
zygapophyses are paired. Farther back the arch shows no trace of 
division into halves and the anterior and posterior zygapophyses unite 
form single median facets. 
The precaudal ribs are double-headed, their capitular and tubercular 
process being comparatively long. The body of the ribs is grooved 
longitudinally on its anterior and posterior surfaces, which must have 
added considerably to their rigidity. Only fragments of slender 
ventral ribs have been found. 
acel. 
\ 
ba lll 
wy 
Fic. 4.—Ophthalmosaurus icenicus, Seeley. Right ischio-pubic bone. A, upper 
(visceral) surface; B, proximal articular end; C, ventral (outer) surface. 
About 4 nat. size. 
acet. acetabular surface ; i/.f. facet for ihum; isch. ischium; 0d.f. obturator 
foramen: pw. pubis; v.b. ventral border. 
The shoulder-girdle has been described and figured by Professor 
Seeley.!. The coracoids are broad plates of bone, greatly thickened in 
their middle portion. Their posterior border is convex, while the 
anterior is concave owing to the presence of a wide, sharply defined 
notch. Internally the coracoids united with one another in a large 
cartilaginous symphysis; externally they bear a short anterior facet 
for union with the scapula and a much larger posterior cartilage- 
covered surface for the humerus. The scapula consists of a narrow 
dorsal blade and an expanded and thickened ventral region, which 
bears a facet for union with the coracoid, and behind this a small 
surface which completed the glenoid cavity in front. On the anterior 
border of the scapule is a roughened surface marking the line of union 
t Quart. Journ. Geol. Soc., vol. xxx (1874), p. 696, pls. xlv, xlvi; also Proe. 
Roy. Soc., vol. liv (1893), p. 151, fig. 1. 
