140 ME. W. K. PAEKEE ON THE STErCTUEE AND 



descending process (Plate XI. fig. 1, n.) : in this young bird the intermaxillaries separate 

 them, the still ununited tips of these bones lying a little over the ethmoid (Plate XL 

 fig. 3, n., eth.). Afterwards, in the adult, the nasals for some distance nearly approach ; 

 for the lengthening of the cranio-facial axis has by this time given a very lacertian short- 

 ness to the nasal processes of the intermaxillaries. Essentially, the lacrymals (Plate XI. 

 fig. 1, 1.), with their long superorbital process and their fenestrate antorbital plate, differ 

 little from those of the Ehea; they are already well grown. The intermaxillaries {px.) 

 have been partly described ; the nasal portion is vastly different from the same process in 

 the Rhea and Ostrich, being almost as feeble as in the Cassowary (Plate XI. fig. Z,px.). 

 The extremely coarse vascularity of this part, as of the corresponding part of the denta- 

 ries, makes the bone like a Madrepore (Plate XI. figs. 1, 2, & 3) ; it is an excellent stru- 

 thious character. The height of this part, in this young one especially, brings DromcBus 

 irroratus very close to Professor Owen's Palapteryx geranUdes (see Zool. Trans, vol. iii. 

 part 5, pi. 54. fig. 1. p. 361). In this embryo the dentary margin of the intermaxillary 

 is 1 inch 3 lines in extent, thus reaching to within 4 lines of the posterior end of the zy- 

 goma (Plate XI. fig. 1, px.), and well illustrating the potency of this most anterior arch, 

 even in so simple and, as it were, elementary a bird as the Emu ; and this is the bird 

 in which I have found the best rudiment of the true maxillary bone (Plate XI. fig. 1, 

 & Plate XIII. figs. 12 & 13, mx.). As in the Meckelian, so in the prenasal cartilage, 

 there has been a much quicker absorption of substance : speaking of class characters, 

 none could be more assuredly set down to the mammalian category ; and the Emu, as 

 one of the Casuarine group, is in many other respects the most outlandish of its class, 

 and one of the nearest feathered relations of the hairy tribes. This early loss of the 

 model has not, however, resulted in an earlier coalescence of the symmetrical splints ; 

 behind the coalesced part of the intermaxillaries the palatine plates (Plate XL fig. 2,px.) 

 are seen — much smaller, however, than in the Ehea, where the dentary margin is so 

 short. The intense interweaving of the members of the struthious group is well seen 

 here ; for the African Ostrich rather sides with the Emu than with the Rhea in the 

 structure of its intermaxillaries, and we shall see that in many points the Dinornis ties 

 the Ostrich to the Emu. As to the prevomer of the Emu (Plate XL fig. 2, & Plate XIII. 

 figs. 12 & l?>,pv.), its anterior process is smaller, and its body longer than in the Rhea, 

 in which the widest part, viz. that bounding the middle nares, is short ; next to it comes 

 Struthio, then Dromseus, and then the Cassowary, in which the length and narrowness of 

 the body of the prevomer rivals that of the Apteryx and the Tinamou. In the Rhea the 

 two retral processes are of the same length ; in the Emu the zygomatic style is very long, 

 the inner style very short ; the Ostrich agrees with the Rhea in this point. A few large 

 foramina are seen on the palatal surface of this bone, which is gently concave ; the upper 

 surface is much more complex, and the bone unexpectedly takes on characters which 

 have their fulness in the various tribes of typical birds. The ascending process (Plate 

 XL fig. 1, n.p.v.) is a mere bud, but more distinct than in the African Ostrich ; the little 

 bony bridge a little in front of this is similar ; but whilst the posterior margin of that 



