58 Messrs. Embleton and Atthey on the 



surfaces a more or less distinct half-facet for a half-head of a 

 rib. The transverse processes are one -inch in length, and have 

 each a concave articular surface on the front of their ex- 

 tremities to receive the tubercle of a rib. The articular 

 processes are sharply defined, their facets nearly circular and 

 fiat ; the anterior pair face upwards and a little inwards, and 

 the posterior downwards and a little outwards. 



Of the ribs, the largest (see Plate VII. fig. 1) is 7| inches 

 long and the distance from head to tubercle 1^ inch ; the 

 heads, necks, and tubercles of the ribs are strong and well defined, 

 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 posterior 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 3^ inches, in breadth at the upper 

 end |- inch, at lower If inch. 



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

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

 pying 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, tlie lesser one more inwards than the 

 greater ; those at the lower end look downwards and inwards, 

 are more on the same plan than the upper pair, and measure 

 respectively 1 inch and f inch in length. 



As no epiphyses appear on any of these bones of Loxojyinia, 

 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 reptiles having been only incidentally mentioned in the 

 course of this paper, we shall now endeavom* 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 j 

 and in so doing we are bound to acknowledge with gratitude 

 the indispensable assistance we have derived from the standard 

 works of Professors Owen and Huxley. 



Loxomma presents all the characters of the order Labyrin- 

 thodontia of Owen, except " two occipital condyles " for articu- 

 lation with the atlas ; and it has, besides, other characters which 

 also show its affinity on the one hand with Fishes, and on 

 the other with Batrachians and the higher Reptiles. 



