AND DEVELOPMENT OF THE BIRD'S SKULL. 119 



(figs. 8 & 9, mxp) they agree in general with those of young Coracomorphse and Hemipods, 

 but in particular with both young and adult of that family of birds which has most 

 similarity to them in general bodily structure, namely Swifts (" Cypselidse"). The 

 process itself is at first a mere hook, moderately thick, rather long, curving at first 

 inwards, and then directly backwards. This perfectly retrorsal rod runs directly along 

 the inside of the palatine; in the Swift it clears itself of the palatine, and is altogether 

 more flattened and sickle-shaped. 



The maxillo-palatine of the " Trochilidse " becomes more and more underlaid by the 

 palatine (figs. 2 & 3), so that a lower view shows little of tbem, and the specimen has to 

 be carefully studied in oblique aspects before its form and relations can be understood 

 (fig. 4, pa, mxp). Then it is seen that the little rod has become a flat thin plate, with a 

 terminal hook, and with its lower edge entirely ankylosed to the palatine. This is similar 

 to the condition of things found in Cranes and Plovers, and totally unlike any tbing seen 

 in the " iEgithognathse." As far as my memory serves me, I have never seen any 

 ankylosis of these parts in the " Coracornorphae," not even in such highly ossified faces 

 as those of JPhytotoma, Coccothraustes, Gymnorhina, or Artamus ; the palatines, even 

 in these, keep scrupulously apart from the overlying maxillo-palatines. 



The huge nasal labyrinth is much more in conformity with its counterparts in the Pas- 

 serinse than the facial bars. The alee nasi (aln), like those of the Hemipods, are large 

 mussel-like valves, and have this special character, namely, that the widest part of the 

 nostril is behind; the teleological meaning of this, structure "lies at the door," like the 

 other specializations of this type. 



Unlike the generality of the small and delicate species of the " Coracomorphae," such 

 as Acanthorhynchus, Nectarophilus, Phylloscopus, Troglodytes, Chelidon, &c, the nasal 

 outworks and walls are extensively ossified. The posterior septal bone is present, and 

 has a smaller ossicle in front of it (fig. 4, sn), and the anterior alar region (figs. 2-6, aln) 

 is ossified right and left in the recurrent lamina (rcc) and in the free valves ; in the 

 latter there is a margin of cartilage left, and this has a selvedge of bone formed by a 

 distinct centre on each side. This is the sickle-shape counterpart of the annular alinasal 

 ossicle of certain Parrots (Melopsittacus undulatus &c). The large alinasal turbinals 

 (atb) are ossified to a considerable extent, the inferior turbinals (itb) scarcely at all. 

 The anterior nasal floor is but little developed ; yet it sends inwards its inturned lamina 

 (ial), a broad unossified flap, to be tied to the vomer by a broad ligament (ial, v). The 

 true olfactory region (ecto- and meso-ethmoids) is of great size, and is densely ossified : 

 thoroughly Passerine, it has completely aborted the lacrymals, and appears on each side 

 of the frontals above (figs. 5 & 6, eetli), whilst below it forms most extensive antorbital 

 wings (pp), the suborbital part of which, reaching two thirds of the way towards the 

 quadrate, has no separate ossification of the " os uncinatum." 



The skull is depressed : grooved above symmetrically for the long hyoid cornua 

 (3rd arch), it has its ethmo-presphenoidal plate (pe) solid, as in the Carp, and non- 

 fenestrate. The orbito-sphenoidal Lips are narrow, and the orbital plates of the frontal 

 very little developed, so that the tilted floor of the cranium is largely membranous. The 



