Dinosaur fr 0771 the Lower Lias. 573 



outline, the lower border being thin and sharp. Anteriorly 

 tlie iscliial process of the pubis is limited by a larfi:e and 

 well-defined obturator notch [o.n ), which, when the bone 

 was unbroken, may have been a closed foramen, though this 

 does not seem likely. Distal to this notch, and separated 

 from it by the prominence forming its anterior border, the 

 shaft of the pubis narrows very rapidly and becomes com- 

 pressed from above downwards; this region is strengthened 

 by a ridge on its inner side continuous with the anterior 

 border of the obturator notch. The distal portion of the 

 bone is wanting on both sides. 



The Ischium (fig. 1, isc). — This bone is represented on 

 the right side by some fragments of its proximal end. A 

 portion of the pubic process is present : this forms the lower 

 border of the acetabulum. It thickens towards the junction 

 Avith the pubis ; its ventral edge is thin and sharp throughout. 

 The relation of the ischium to the ilium is obscure ; there 

 does not seem to have been a definite ischial process on the 

 ilium. Immediately behind the acetabulum there is a deep 

 rugose pit, from which a foramen (/.) penetrates to the 

 inner face of the bone. It is doubtful whether this pit is 

 borne by the ilium or the ischium, but it seems to correspond 

 in position with the rugosity on the ischium of Ornitholestes 

 figured by Gregory and Camp (Bull. Amer. ]Mus. Nat. Hist. 

 vol. xxxviii. (1918) pi. xlvi.), and regarded by them as 

 serving for the origin of the flexor tibialis intcruus (semi- 

 membrjinosus) muscle, 



The Femur (fig. 2, A, B). — The femur of the left side was 

 found associated with the pelvis, but, unfortunately, it is 

 badly preserved. The head is broken away, as also is the 

 end of the fourth trochanter. The distal end is much 

 crushed, and the condyles are wanting. The bone, as a 

 whole, is rather strongly curved, the convexity being in 

 front. The middle part of the shaft is nearly cylindrical, 

 but tends to widen out towards the ends, particularly 

 distally. The summit of the bone, just external to the 

 fractured surface which marks the loss of the head, bears a 

 shallow pit (;j.), beneath which on the outer side of the 

 hone there is a narrow flat surface running down to the 

 tr®chanteric shelf (t.s.), described below. The anterior face 

 of the upper end is also nearly a flat surface, terminating 

 below in the notch formed by the peg-like anterior (great) 

 trochanter (gtr.). From the base of this projection a 

 shelf-like surface {t.s.) runs back to the posterior border of 

 the bone. From the base of the trochanter a strong 

 roughened ridge runs down the shaft towards its inner 



