1872.] DR. J. ANDERSON ON MANOURIA AND SCAPIA. 141 



bral is only a little longer than broad ; and its posterior is contained 

 more than twice in the anterior margin of the plate, and equals thj 

 anterior lateral margin, which is about one half of its own length less 

 than the posterior lateral margin. The length of the fourth vertebral 

 slightly varies. The fifth vertebral has seven margins, if the caudal 

 sutures are counted as two, which they are. The length of the 

 shield is slightly variable ; but it is always broader than long ; the 

 anterior lateral margin, which is the broadest, only slightly exceeds 

 one of the caudal sutures. The greatest breadth of the two caudals 

 exceeds the breadth of all the vertebrals, but approximates to the 

 fifth. Each vertebral and costal has a central, slightly elevated 

 areola, with concentric grooves external to it, the areolae being most 

 prominent on the first and fifth vertebrals and on the first costal. 

 On the costals the areola is slightly above, and on the marginals 

 slightly below their centres, and in the latter it is somewhat de- 

 pressed, not convex as on the other shields, and has the lateral ridge 

 continuous with the free margin of the shell immediately above it. 

 The gular plates are subject to variation ; they may be either more 

 or less quadrangular, or the figure may be modified to the triangular. 

 These fignres depend on the angle at which the external margins of 

 the plates are placed to their common suture. The two plates an- 

 teriorly are separated by a rather deep notch, but not so marked 

 as the anal, which is broad and deep. The concave sterna have the 

 pectoral plates separated by an interval of variable extent, but in none 

 do the pectorals touch each other ; while the flat sterna have the pec- 

 torals forming a suture of variable dimensions. When the suture is 

 broad, the external margin of the pectoral plate is in connexion with 

 one half of the internal margin of the fourth marginal, and with the 

 whole of the same border of the fifth marginal, forming also a very 

 small suture with the sixth marginal ; while, when the pectoral suture 

 is narrow, or when the plates are apart, the fifth marginal forms a 

 suture with the abdominal plate. In others, when the pectorals ap- 

 proximate without touching, however, this contact of the fifth mar- 

 ginal and abdominal plates is reduced to a very small surface, so that 

 the pectoral nearly touches the sixth marginal plate. The axillaries 

 and inguinals are small ; and there are usually two of each, the most 

 external being the largest. 



The colour of the shell varies with age : in the young it is a dull 

 olive-brown, the areola being light greenish and horny, while in the 

 adult it is wholly black. 



The head is of nearly equal depth throughout, nearly flat on its 

 upper surface behind, and slightly arched above before the eyes to 

 the tip of the snout, which projects beyond the nostrils, which are in 

 a line with the inner angle of the eye. The loreal region is rather 

 narrow and concave. The front of the upper jaw is convex from above 

 downwards, from the nostrils to its lower margin, which projects very 

 slightly beyond the lower jaw. There is a feeble ridge from the outer 

 border of each uostril to the margin of the upper jaw, and a more 

 obscure median ridge between the nostrils. The symphysis of the 

 lower jaw is convex downwards and backwards, the under margin of 



