ON THE OSTEOLOGY OF NYCTOSAURUS. 147 
MEASUREMENTS. 
, mm. 
ESR a ee go Ba ede Aono kad edete sane woep 211 
DIET e ECOL. os Oat os ena ee ee au oe go eos oe L7te 
SMMEMIR TIN Trew NITOG ye ites no eee Cee teas eee ee Sane ene SG, IO 
Ce ee CSCC Be ee ec een Sete bea wa eee 8,9 
Oh oS 06 Pee Ney NE Sa ee PE ses g, 10 
The ¢hird phalange has the proximal extremity preserved, com- 
pressed from above. ‘The surface seems to have been only slightly con- 
cave. This phalange, like the preceding one, seems to have been pro- 
portionally more slender than in Preranodon. 
PELVIC GIRDLE AND EXTREMITY. _ 
Pelvis. Pl. XLI, Fig. 1. ‘The pelvis lies with the bones nearly in 
position, the sacrum with its ventral surface uppermost, the innominate 
bones separated at their sutures and in juxtaposition with the sacrum, the 
visceral surface also uppermost. 
‘There was in the sacrum (Pl. XLI, Fig. 1, s) in life evidently a 
considerable concavity transversely, and possibly a slight concavity longi- 
tudinally. It is composed of six firmly united vertebrz, the sutural lines 
between the centra clearly distinguishable. The vertebra decrease in 
length from the first to the fifth; the sixth is slightly longer than its 
predecessor. ‘The centra are flattened in the preserved specimen, though 
possibly in life they may have been slightly convex transversely. The 
sacral ribs show no indications of sutural connections anywhere, and are 
broadly united distally. Between them the oval foramina decrease rapidly 
in size, and slightly approach the middle line, the last, that between the 
fifth and sixth vertebrz, being almost punctiform, while the first is of 
considerable size. 
The first process is broad, with a broad, oblique surface, terminating 
distally in a free, rounded margin. The pelvic brim is indicated by an 
angular line passing outward and downward obliquely to the upper 
border of the articular surface for the innominate bone. This surface is 
oval, and encroaches obliquely on the front surface of the sacrum; beyond 
it the thin margin of the sacrum does not present a sutural surface on the 
ventral side. The lateral margins approach each other until at the hind 
border the distance between them is less than half that at the brim of 
the pelvis. 
The z/tum (Pl. XLI, Fig. 1, 27) has a long, flattened or somewhat pris- 
matic anterior process, reaching as far forward as the second presacral 
_ vertebra. The process is apparently curved somewhat backward in life, 
and also outward; it has an obtuse anterior extremity. Posteriorly the 
