SAUROPTERYGIA. 119 



premaxilla very large ; a parietal foramen in the adult ; a transverse 

 bone ; a distinct prefrontal ; postorbital in some cases separate from 

 postfrontal; and mandibular symphysis uniting by suture. Teeth 

 with sharp curved crowns and fluted enamel ; implanted in distinct 

 sockets, and confined to the margins of the jaws. Each rib articu- 

 lating to a single vertebra : and in the cervical region the costal 

 facets single or double ; caudal ribs present. Vertebras amphiccelous, 

 with the neuro-central suture persistent or obliterated ; costal 

 articulations on the centra of the cervicals and caudals, and on the 

 arches of the dorsals * ; the latter usually having distinct transverse 

 processes. Chevrons present. In the pectoral girdle 2 the coracoids 

 uniting in a ventral symphysis ; and the scapulae either meeting in 

 the median line, or more or less widely separated by the intervention 

 of a single or triple ossification correlated by Hulke with the omo- 

 sternum ; the clavicles and interclavicles according to this view 

 being wanting. Limbs variable, being apparently adapted in part 

 for progression on land in the more generalized, but converted into 

 paddles in the more specialized forms ; humerus and femur always 

 of considerable length; phalangeals elongated, and no additional 

 digits developed. 



Habits carnivorous ; marine or terrestrial. 



A remarkable peculiarity of the limb-bones is worth notice. In 

 the later forms at least the terminal epiphyses of the humerus and 

 femur were enormously developed, forming two cones (fig. 46, p. 149), 

 which may meet at their apices in the middle of the bone, and thus 

 reduce the shaft to what may be described as a pair of cups united 

 together at their bases, and having deeply conical cavities. 



The skull has a parieto-squamosal (post-temporal) bar. 



1 The vertebrae in which the costal articulation is partly on the arch and 

 partly on the centrum may be termed " pectoral " in the anterior, and lumbo- 

 sacral or lumbar in the posterior region of the column. 



2 Great difference of opinion has arisen in the interpretation of the pectoral 

 arch. Seeley regards the portion here termed omostcrnum as the clavicle and 

 interclavicles, and considers, with Huxley, that the whole of the bone here 

 termed scapula really is so. Hulke, however, Proc. Geol. Soc. for 1883, 

 pp. 45-50, regards the ventral plates ( po, or j>.cor. of figures) of these bones as 

 corresponding to the precoracoid of t!.c Chelonia ; a correlation which is some- 

 what difficult to accept in view of their absence in JS"othosaurus. The deep- 

 seated position of the bones termed oinoslenium appears to be in favour of 

 Hulke's interpretation. The suggestion thai the ventral plates of the soapulsa 

 are clavicular is clearly untenable. 



