Vol. XII. 



1913 



1 Shufeldt, Osteology of Cereopsis novce-hollandicB . 213 



hyhrida, to be entirely absent in Cereopsis, where that apophysis 

 is completely rounded off. 



Hymenolxmtts malacorhynchiis has a thin and fragile superior 

 osseous mandible — elongate, with comparatively small external 

 narial apertures ; sharp tomia ; deeply concaved on its under side, 

 and with its distal end squared rather than rounded as in the Geese. 

 (Fig. 3, Plate XXVIII., fig. 17, Plate XXX., fig. 20, Plate XXXI.) 



Viewing the skull of Cereopsis on its posterior aspect, we are 

 to note that the usual landmarks, often found there in the avian 

 cranium, are but feebly pronounced. The entire area is more 

 or less globular or rounded, with the occipital ridge and the 

 crotaphyte jossce but faintly defined. The supra-occipital prom- 

 inence hardly exists as an independent elevation, while the 

 foramen on either side of it is extremely, or at least very un- 

 usually, small. Of good size, the foramen magnvm is subcordate 

 in outline, and the condyle for the atlas notched on its upper side 

 in the middle. Anser albifrons ganibdi has all the characters at 

 the back of its cranium in complete agreement with what I 

 have just given for Cereopsis. To a large extent, this applies to 

 Chen hyperhoreus ; but in the genus Chen the occipital ridge may 

 be somewhat better defined, though it is not always so. In. 

 Branta this is invariably the case, while the occipital prominence 

 is far more conspicuous in members of that genus, especially in 

 Branta canadensis. 



In Tachyeres cinereus the posterior aspect of the cranium 

 differs, in each and every character, from what we meet with in 

 Cereopsis ; for in the former the crotaphyte fosscB are deep and 

 sharply defined ; the occipital ridge prominently produced ; the 

 occipital prominence much elevated, and the large, vertically 

 elliptical foramen on either side of it seems, with respect to its 

 presence and absence, to depend upon age in this Goose, as it may 

 in other genera of this group. In the skull of one individual of 

 this species at hand (No. 1,819, Coll. U.S. Nat. Mus.) these 

 foramina are almost entirely absorbed, being quite minute, with 

 the prominence standing between them of slight elevation. On 

 the other hand, in another skull they are, as I have stated above, 

 large and elliptical in outline, with the supra-occipital prominence 

 much better defined (No. 1,818, Coll. U.S. Nat. Mus.) (Fig. 23, 

 PI. XXXII.) In both these skulls the foramen magmim is somewhat 

 acutely cordate in outline, the apex being above. This is like- 

 wise its form in HymenolcBmiis malacorhyncJtus — that is, in the 

 skull at hand, wherein, too, the shallow crotapJtyte fossce are 

 extensive, especially below. 



Regarding the skull of Cereopsis novcB-hollandice in lateral view, 

 we observe that the aural aperture or external auditory meatus is 

 large and open, with its periphery of a subcircular outline (Fig. i, 

 Plate XXVIII.) A lengthy s phenolic process is developed, directed 

 downward and forward, terminating in a free, truncate apex, at 

 a distance of some 5 or 6 millimetres from the apex of the 

 descending process of the lacrymal. So far as I am aware, these 



