CLASSIFICATION, AND PHYLOGENT OF THE DJNOEXITHID^. 383 



to Mcsoi)teryx, species y (figs. 30 & 44), and Emeus, species y (fiqs. 34 & 40), differ from 

 the other species of the genera in which I have provisionally placed them in possessing 

 a distinctly right-angled orbit. 



The anterior part of the cranial roof, between the preorbital processes, is formed 

 partly by the frontals, partly by the nasals. The junction between the two bones is 

 well shown in the young skull of Anomalopteryx didiformis (figs. 12 & 17), in which, 

 the nasals being lost, each frontal is seen to present a deep triangular notch for the 

 lateral portion of the corresponding nasal, while between the notches the frontals end 

 in a straight transverse border, with which both the mesial portions of the nasals and 

 the nasal process of the premaxilla articulate. 



The nasals are in contact by their ventral surfaces with the ethmoid, exposed by 

 their removal in figs. 12 & 17, and unite with one another in the middle line beneath 

 the premaxilla, for the reception of whicli the mesial portion of the conjoined bones is 

 excavated in the form of a shallow, parallel-sided groove, the premaxiUary fossa 

 (figs. 23 & 34). Thus the mesial portion of the nasals is hidden in the entire skull, 

 and the roof of the olfactory chamber is formed in this region of a triple layer of 

 bone — premaxilla externally, ethmoid internally, and nasals between. Laterad of the 

 premaxillary fossa the nasal appears on the surface as a triangular bone the curved 

 base of which forms the posterior boundary of the nostril (figs. 5, 7, & 8), its external 

 angle being produced, in a young specimen of Anomalopteryx didiformis, into a short 

 maxillary process. In Dinornis torosus this process is continued as a slender bar of bone 

 which passes vertically downwards, in close contact with the anterior border of the 

 lacrymal (preorbital process), completing the lacrymal foramen externally, and articu- 

 lating by its lower or distal end with the maxilla. In Emeus, species a, and E. crassus 

 this process is represented by a distinct ossification which I propose to call the 

 maxillo-nasal (figs. 7 & 8, mx.na.). I have been unable to ascertain the precise 

 condition of these parts in the other genera, but I am inclined to think there is a 

 distinct maxillo-nasal in Anomalopteryx, while in Pachyornis there appears to be a 

 maxillary process as in Dinornis. 



In the skull referred to Mesopteryx, species /3, the anterior portion of the skull-roof 

 is marked with numerous shallow pits arranged more or less regularly in lines 

 radiating backwards and slightly outwards from the edges of the premaxillary fossa 

 (Plate LX. fig. 20). They appear to indicate the presence of a crest of specially strong 

 feathers, which must have consisted in the present case of paired tufts, since the pits 

 are absent in the middle line. In the type specimen of Dinornis torosus, and in the 

 specimen of D. robustiis {I), potens, Hutton) in York Museum, similar pits occur, 

 extending across the middle line and on to the preorbital processes. Similar but less 

 distinct pits occur in two skulls of Anomalopteryx didiformis. Since in the two last- 

 named species the pits are absent in certain skulls, it seems probable that the crest 

 was possessed only by the male. 



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