68 Geological Society. 



in its triedral figure, and the flatness of the sides, none of which are 

 longitudinally grooved. It resembles most the humerus of the Al- 

 batross in its form, proportions and size, but it differs in the more 

 marked angles bounding the three sides. The expanded extremity 

 likewise resembles the distal end of the humerus of the Albatross, 

 but it is too mutilated to allow the exact amount of similarity to be 

 determined. 



On the supposition that this fragment is really a part of the hu- 

 merus, Mr. Owen says, its length and comparative straightness would 

 prove it to have belonged to a longipennate natatorial bird, equalling 

 ill size the Albatross. 



The two other portions of bone have been crushed, but Mr. Owen 

 states that they belong to the distal end of the tibia, the peculiar 

 strongly-marked trochlear extremity of which is well preserved. 

 Their relative size to the preceding bone, supposing that specimen 

 to be part of a humerus, is nearly the same as in the skeleton of tne 

 Albatross. There is no bird now known north of the Equator with 

 which the fossils can be compared. 



Tortoise. — The remains of the Chelonian Reptile consist of four 

 marginal plates of the carapace, and some small fragments of the 

 expanded ribs. The marginal plates are united by the usual finely- 

 indented sutures, and each is impressed along the middle of its up- 

 per surface with a line corresponding to the margin ol" the horny 

 plate which originally defended it. The external edge of each plate 

 is slightly emarginated in the middle. These plates are narrower 

 in proportion to their length than in any of the existing marine Che- 

 Ionia; and they deviate still more in the character of their internal 

 articular margin, from the corresponding plates of terrestrial Che- 

 Ionia; but they sufficiently agree with the marginal plates of the 

 carapace of the Emydes, to render it most probable that these cre- 

 taceous remains are referable to that family of Chelonia which live 

 in fresh water or estuaries. 



Lacertian Saurian. — This fossil belongs to the collection of Sir 

 Philip Egerton ; and it consists of a chain of small vertebrae in their 

 natural relative position, with fragments of ribs and portions of an 

 ischium and a pubis. 



The bodies of the vertebrae are united by ball and socket-joints, 

 the socket being on the anterior and the ball on the posterior part 

 of the vertebra ; and they are further proved to belong to the Sau- 

 rian class of reptiles by the presence of many long and slender ribs, 

 as well as by the conversion of two vertebrae into a sacrum, in con- 

 sequence of the length and strength of their transverse processes. 

 The remains of the ischium and the pubis are connected with the 

 left side of the sacrum, proving incontestably that this reptile had 

 hinder extremities as well developed as in tiie generality of Sau- 

 rians. Of these extremities, as well as of the anterior and of the 

 head, there are no traces. 



Mr. Owen then proceeds to determine to which division of Sau- 

 rians, having ball and socket vertebral joints, the fossil should be 

 referred. In the crocodilian or Loricate group, the transverse costi- 



