220 DR. EMBLETOX AND MR. ATTHEY OX THE 



a little inwards, and the posterior downwards and a little out- 

 wards. 



Of the ribs, the largest (see Plate IV., tig. 1) is seven inches 

 and seven-eighths long, and the distance from head to tubercle 

 one inch and three-sixteenths ; the heads, necks, and tubercles 

 of the ribs are strong and well denned, and there is a well 

 marked groove on both surfaces running almost from end to end 

 of the bones. The tubercle has an articular facet on its pos- 

 terior face for the transverse process of a vertebra. 



Out of the bones of the extremities it is not possible to con- 

 struct a single paddle ; there is only one humerus, no femur, nor 

 are there any other bones of the anterior or posterior girdle. 



The humerus is somewhat elongated, flattish, more convex on 

 its outer than on its inner surface, broad below, narrow at the 

 upper end ; in length three inches and a half, in breadth at the 

 upper end three-quarters of an inch, at the lower one inch and 

 five-eighths. 



At each end is a pair of articular facets ; these are differently 

 disposed. The facets at the upper end differ in size, one occupy- 

 ing the whole of the end, the other being placed at the inner 

 margin of the posterior part of the former ; both face upwards 

 and inwards, the lesser one more inwards than the greater ; those 

 at the lower end look downwards and inwards, are more on the 

 same plane than the upper pair, and measure respectively one 

 inch and five-eighths of an inch in length. 



As no epiphyses appear on any of these bones of Loxomma, the 

 animal must have been adult, though of rather smaller size than 

 some others the bones of which have been brought to light. 



VI. Some of the relations that Loxomma bears to Fishes and 

 Eep tiles having been only incidentally mentioned in the course 

 of this paper, we shall now endeavour to bring together such of 

 them as at present occur to us, who are very far from being 

 deeply versed in the intricacies of comparative anatomy ; and in 

 so doing we are bound to acknowledge with gratitude the indis- 

 pensable assistance we have derived from the standard works of 

 Professors Owen and Huxley. 



