Vol. XII 

 "913 



] Shufet-DT, Osteology of Cereopsis novcp-hollandice. 215 



c. hutchinsi, while in Chen hyperborens it may be entirely absent 

 in the adult. 



Usually, the inter-orbital septum is very completely ossified, as 

 it is in Cereopsis, where it is thick, and the usual foramina for the 

 exit of the nerves, at the back and lower part of the orbit, are 

 exceptionally small and thoroughly individualized. (Fig. i, Plate 

 XXVIII.) In any of these wild Geese, so far as I have examined 

 the skulls of them, if any vacuities exist in the mesial or posterior 

 orbital walls, they occur in the upper or the posterior one, or 

 both, and thus lead into the cranial cavity. This is the case in 

 Chen, Anser, and Branta among the Anserincv, also in Hymeno- 

 IcBmiis among the Merganettince, and others. 



The infra-orbital or zygomatic bar is a straight, slender rod in the 

 skulls of all the species of Geese thus far referred to, including 

 Cereopsis, as will be appreciated by a glance at figs, i, 3, 4, and 

 others shown on the plates. Anteriorly, it thoroughly fuses at 

 its articulation with the several bones it meets, as the palatine, 

 maxillo-palatine, nasal, and premaxillary. 



Seen upon side view, the great spongy, osseous maxillo- 

 palatine in Cereopsis novcB-hollanclicB rises above its articulation 

 with the bones below, to articulate with the posterior border of 

 the nasal, with the lacrymal, and, to some extent, with the 

 premaxillary, thus quite shutting out from sight, on this view, 

 the fellow of the opposite side, as well as any of the structures in 

 the posterior pai't of the rhinal space. To a lesser extent this is 

 likewise the case in Branta canadensis ; but in this typical wild 

 Goose the ascending plate of the maxillo-palatine is thin, and its 

 spongy formation is not overlain with compact osseous tissue, as 

 it is in Cereopsis. As a rule, it does not meet the lacrymal, but 

 extensively fuses with the opposite maxillo-palatine, with the 

 posterior border of the nasal, and with the upper surface of the 

 palatine of the same side, thus forming the typical desmognathous 

 arrangement which is characteristic of all the true Anser es. With 

 respect to this arrangement, Branta c. hutchinsi agrees with B. 

 canadensis, as do likewise representatives of the genera CJien and 

 Anser. It is different, however, in Tachyeres cinereiis, where it 

 is situated low down, being concave internally, correspondingly 

 convex externally, and thoroughly fused with the mesial surface 

 of the nasal and the inner border of the palatine ; and, while it 

 comes extensively in contact with the maxillo-palatine of the 

 opposite side, the suture generally remains ununited. The distal 

 end of the vomer may or may not reach these maxillo-palatines 

 in the middle line — generally not. So low down are the maxillo- 

 palatines placed in the skull of this Duck of the Falklands that 

 an extensive open space is left above them, admitting of a con- 

 siderable view, from side to side, through the skull, above the 

 vomer and below the fronto -lacrymal roof. (Fig. 23, PI. XXXII.) 

 In all this, Hvmenolcsmus malacorhvnchiis among the Merganettince 

 essentially agrees, as will be seen by comparing the skull of that 

 bird with others shown in the plates (figs. 3 and 23, &c.) 



