542 H. GOVIER SEELEY ON MAUISATTRTTS GARDNERI. 



no indication of this enormous number of vertebrae or length of 

 neck ; but the vertebras are quite as large, and are larger than in 

 any British long-necked Plesiosaurian hitherto described. 



The Tooth. (PI. XXIII. fig. 1.) 



The tooth is perfect, and measures 1| inch in length. The crown 

 is | inch long ; it is curved inward and backward, and is flattened 

 somewhat on its external aspect. The crown terminates in a point, 

 and is marked with fine close-set parallel striations rather finer than 

 is common among Plesiosaurs. The fang continues to expand for half 

 its length, and then contracts somewhat towards the base, so that the 

 convex anterior outline of the tooth is an arc of a smaller circle than 

 the concave posterior border. It is difficult to estimate the size of the 

 head from a tooth ; but it probably did not exceed a foot in length. 



The Vertebral Column. 



The earliest vertebra preserved is an early cervical with the 

 neural arch and cervical ribs ankylosed to the centrum. These 

 short ribs give a subtriangular appearance to the articular surface, 

 which is modified a little by the lateral widening of the neural arch. 

 The antero-posterior length of the centrum is ly 1 ^- inch ; the depth 

 of the centrum is 1§ inch ; and its breadth on the anterior face is 

 1-2- inch. The articular face is flattened, moderately concave, and 

 most compressed from front to back at the base of the neural arch. 

 The base of the centrum is marked with an elevated median ridge. 

 The short ribs are given off from the inferior lateral corners of the 

 centrum, and, as usual, are directed outward, backward, and down- 

 ward. The neural canal is large and vertically ovate ; the neural 

 arch is constricted from side to side at the base of the neural canal ; 

 it has a subquadrate aspect as preserved, but is too imperfect for 

 description. I am aware of no data on which to determine the 

 number of vertebras which were anterior to this one, or which inter- 

 vened between it and the next preserved. 



The second of the series has the centrum nearly 3 inches long, 

 with the articular ends flattened and slightly concave, and the 

 margins of those surfaces slightly rounded. The centrum has an 

 elongated constricted appearance, and has the compressed, elongated, 

 elevated, articular area for the cervical rib at the base of the lateral 

 aspect ; but the specimen is too badly preserved to admit of 

 measurement. 



Many vertebraa are missing between the second and the next pre- 

 served : for although the third is only 3| inches long, it has nearly 

 twice the transverse diameter of the second. The articular faces, 

 still a little concave, are transversely ovate, about 3f inches wide, 

 with the centrum 2| inches deep in front and deeper behind. The 

 edges of the articular margin are slightly bevelled. The base of the 

 centrum has a strong median ridge, which becomes broader towards 

 each articular surface. On each side of the base, between this ridge 

 and the rib, is a large impressed crescentic area. The transverse width 



