Cope.] ^Ub [March 18, 



not horizontally produced on external face. Articular and surangular 

 united. Splenial moderately elongate ; dentary extending behind coro- 

 noid on external face and deeply notched. Angle short, horizontal, with 

 short internal angle. Five cervicals with intercentra in S. undulatus 

 and six in 5. spinosus ; three without ribs in both. Ribs extending to 

 sacrum. Sacral centra not coossitied. Sacral diapophyses coossified dis- 

 tally ; the second with a posterior free angle distally. Caudal diapophyses 

 well developed at base of tail. From about the eighth caudal the centra 

 are segmented in front of the middle. 



Scapula with proscapular process ; coracoid with one notch. Sternum 

 with a very large fontanelle. Two ribs join the sternal plate ; one comes 

 off the base of the xiphoid rod, and two articulate with the latter ; total, 

 five pairs. The ilium has a small angulus cristce, and the acetabulum is 

 not emarginate behind. The pubes are nearly transverse, and the pecti- 

 neal angle is external. The ischia are rather slender, and the tuber is 

 an angle. 



The middle and posterior teeth are feebly tridentate; the others are simple. 



PHKYKOSOiiA Wiegmann. 



The following account of the osteology is derived from the skeletons of 

 three species, the P. douglassii, P. cornutum and P. coronatam. The de- 

 scription applies equally to each of these species unless otherwise stated. 



The premaxillary has a very short alveolar portion which does not 

 bound the nostrils below (or very little P. coronatuni). It has a superior 

 spine and concave palatal border. The nasals are di^tinct and are exca- 

 vated in front by the large nareal openings. The frontal is single, is 

 much narrowed in front by the prefrontals, but extends transversely pos- 

 terior to the orbits, where it sends forwards an acute process in the super- 

 ciliary angle. The prefrontal is large and extends posteriorly to or be- 

 yond the middle of the supraorbital border. It sends posteriorly an acute 

 superciliary process, which meets that of the frontal from behind, over 

 the eye in P. cornutum ; does not quite meet it in P. coronatum, and fjiils 

 to meet it by a longer interval in /'. douglassii. The lachrymal is small 

 and is not reached by the anterior angle of the jugal. The parietal 

 is broad and short, and the pineal foramen pierces it at the coronal 

 suture. Its lateral border is very little decurved to meet the petrosal. 



Its strong parietoquadrate arch supports a liorn or luberosit}', and in 

 most of the species the middle of the posterior border supports the same. 

 The occipital is broadly articulated with the parietal in P. douglassii and 

 P. coronatum ; in the former loosely, in the latter closely. In P. cornutum 

 it affords a narrow but firm support for the parietal. Paroccipital small, 

 visible from behind. Tlie postfrontal is visible as a rudiment in P. dou- 

 glassii, but it is apparently coossified in the two other species. The post- 

 orbital is slender, expanding below for union with jugal and supratem- 

 poral. The former bears two sharp tuberosities in P. coronatum, and the 

 supratemporal two. In P. cornutum there is none on the jugal but there 



