HuTTON. — On a Neio Plesiosaur. 357 



and 55mm. in the most posterior. The cups are simply con- 

 cave, without any flattening or tubercle in the middle. The 

 chevron bones were not auchylosed to the centra. One of 

 these (PI. XLII., fig. A, c.v.), lying on the surface alongside 

 the vertebra which is the last but two in the series, is 40mm. 

 in length, and the two limbs are 28mm. apart at their ends. 

 Two others are seen lying on their sides, each being 4:3mm. in 

 length and 14mm. in breadth. As the ventral surfaces of all 

 the caudal vertebrae are missing, it is impossible to say whether 

 these chevron bones were or were not attached to the centra 

 by longitudinal ridges. 



Bibs. — The shafts of four displaced pectoral ribs (p.r.) are 

 partially exposed on the right side of the animal at and just 

 below the coracoid. They are thick and strong, and slightly 

 compressed, their diameters being about 20mm. and 16nmi. 

 Several abdominal ribs (a.r.) show on each side, and these are 

 but little displaced. They are more slender than the pectoral 

 ribs, their diameter being only 13mm. The external surface 

 is rounded and longitudinally striated, while the internal 

 surface is flattened, and has a deep and broad longitudinal 

 groove. 



Pectoral Arch. — The coracoids (co.) are but slightly dis- 

 placed, and the two still touch each other anteriorly. They 

 are longer than broad, deeply notched in front, concave on the 

 outer margin, and convex on the posterior margin. The inner 

 margin is also apparently concave. I am aware that in the 

 plesiosaurs the coracoids are often thin and broken in the 

 middle, but that is not the case with this specimen. In it the 

 inner margins are smooth and rounded, and that of each cora- 

 coid is symmetrical with that of the other, which could not be 

 the case if they were broken. Consequently the coracoids 

 must have been separated by a large fontanelle in the middle, 

 and have touched anteriorly and posteriorly only, as repre- 

 sented in the diagram (PL XLII., fig. B). At the anterior sym- 

 physis the bone curves ventrally so as to make a longitudinal 

 keel with its fellow. The inner anterior corner is broken, and 

 •we cannot say how far it projected forward, or whether it ar- 

 ticulated with a pro-coracoid. The antero-posterior length of 

 the coracoid is 10-5in. Its anterior breadth, from the posterior 

 end of the glenoid cavity, is 6-5in., its posterior breadth is 5in., 

 and the breadth in the middle is 2-5in. Only the post-axial 

 extremity of the scapula remains, and it is too fragmentary to 

 afi"ord any reliable characters. The proximal end of the 

 humerus is 2-5in. in diameter, and at a length of 3*5in. from the 

 end it has expanded to a breadth of 4 -Sin. This end of the 

 humerus is not well preserved, and it cannot be ascertained 

 whether it bore any trochanterial ridges. 



Pelvic Arch. — This is but slightly displaced, and better 



