268 



CAPT. D. M. S. WATSON ON SEYMOUMA, 



succeeding vertebrae, with the incomplete right scapula, coracoid, 

 and clavicle attached by matrix, the occipital region and part of 

 the right side of the skull and lower jaw, the lower end of a 

 radius and ulna, and a metacarpus. The associated skeleton is 

 represented by a sacral and nine presacral vertebrae, an incom- 

 plete femur and ischium. 



Another specimen collected on West Coffee Greek consists of 

 numerous fragmentary bones of a young individual washed 

 perfectly clean. I also obtained certain isolated bones. 



This material and the new preparation of that at Munich 

 allow me to add materially to our knowledge of the structure of 

 this most interesting form, perhaps the most perfect annectant 

 type known to us. 



Skull. 



Profs. Broili and Williston have given a satisfactory account 

 of the upper and lateral surfaces of the skull. The Munich 

 skulls and that of my skeleton give an equally complete know- 

 ledge of the occiput and palate. For reference I shall refer to 

 that Munich skull which has a shoulder-girdle belonging to it 

 as A, the other as B. 



Basioccipital. — This bone is very well shown in my skull. It 

 is a small bone, remarkably thin dorso-ventrally and of consider- 

 able width. The dorsal surface appears to be completely covered 

 by the exoccipitals and forms no part of the floor of the brain- 

 cavity. The posterior surface forms part of the condyle, which 

 is wide from side to side, shallow and rounded. The ventral 

 surface is widely exposed as a quadrangular area bounded in 

 front by the suture with the basisphenoid. The posterior part 

 of the lateral border is in contact with the exoccipitals, in advance 

 of which it is cut out into a shallow notch, the lower border of 

 the fenestra ovalis. Anteriorly the lateral margin is produced 

 downward and outward to take part in the formation of the 

 tuber basisphenoidalis. 



Basisphenoid. — The basisphenoid is completely known, so far 

 as concerns its inferior surface, from the Munich skulls and that 

 of my skeleton. 



Posteriorly it has a suture with the basioccipital, the ends of 

 which lie on the summits of the well-marked tubera. From the 

 tubera a pair of prominent ridges run forward on the ventral 

 surface, so that this face forms a smooth concavity between them. 

 At the level of the basipterygoid processes these ridges die out, 

 so that the surface becomes gently convex. The basipterygoid 

 processes (shown in Munich A & B) are extremely short and end 

 in a flat articular surface, which does not directly support the 

 pterygoid but is attached to a separate small bone very clearly 

 shown in Munich B. The lateral surface of the basisphenoid, 

 between the tuber and the basipterygoid process, is concave and 

 passes indistinguishably into that of the prootic. About three 

 millimetres above the lower edge of the tubera a minute foramen 



