II 



TERRA NOVA" EXPEDITION. 



comprises a single species. N. aryentina, A.meghino,* from Patagonian deposits thai 

 were at first stated to Ke Cretaceous, but may prove to lie Miocene. 



In Miolania (Fig. 8, B) the skull, seen from above, is somewhat oblong in form, 

 with the snout broadly rounded. The dermal bosses all have the appearance of separate 

 elements, (hi the upper surface inav be recognised a large but low parietal pair: 

 behind them is an occipital pair that project backwards, and in front of them a 

 smaller frontal pair mesially, and a post frontal pair laterally. A pair of subcorneal 

 bosses, rounded or ovate in transverse section, on each side of the parietal pair, project 

 as lateral •'horns": a much smaller pair are placed directly in front of them. Other 

 features of the genus that may be mentioned are that the praemaxillaries have a 

 median pit for the reception of the symphysial beak of the mandible, thai the 

 palatal extensions of the praemaxillaries and maxillaries bear two sharp ridges within 



Fig. 8. -Skulls of A. Niolamia argentina, and I'., Miolania oieeni, sen from above. In B the position of 



I lie anterior margin of the praemaxillaries is indicated by a dotted line. 



and parallel to the margin of the upper jaw. that the nasals project beyond the 

 praemaxillaries. and that there is a bony internasal septum. 



In Niolamia (Fig. 8, A.) the skull is nearly triangular in outline, with the snout 

 more acute than in Miolania. The bosses differ considerably from those of Miolania, 

 as there are three instead of two parietal bosses, the occipital pair are enormous laminar 

 expansions, the lateral " horns " are broad and Hal. triangular in section, and have no 

 smaller pair in front of them. Further differences from Miolania are thai the prae- 

 maxillaries are not pitted, the mandible is not beaked, the upper jaw has a single 

 Muni intramarginal ridge, the nasals do no1 project beyond the praemaxillaries, and 

 l here is no internasal sept um. 



These differences have already been pointed out by Dr. Smith Woodward (Proe. 

 Zool. Sue. L901, i. pp. L74-176), but he has not insisted on them so much as on 



' W Iward, Proc. Zool. Soc, 1901, I, p. 170, pis* x\ win. 



