118 MR. W. K. PARKER ON THE STRUCTURE 



cartilage has been macerated away. Besides the absence of the vomerine cartilages, we 

 have, then, in the " Trochilidse," a lax relation of the vomer to the alinasal wall (see 

 figs. 2, 3, 8, 9, v, ial), the two being connected by a fibrous ligament. But the bone is 

 well shouldered, and above the broadish part the additional bones are seen, namely, the 

 " septo-maxillaries " (figs. 2-4, smx), so that the morphological elements are all here 

 except the pair of vomerine cartilages ; yet the metamorphosis of the parts is arrested 

 and the elements remain distinct. Besides the paired septo-maxillaries (smx), there is an 

 odd one, lying on the vomer, below the septum nasi, and in front of the small pair of centres 

 (fig. 4, jmx). These three'loones coexist in certain iEgithognathse, as Gymnorhina, where 

 they all coalesce with the vomer, and Homorus, where the median piece remains distinct- 

 This azygous piece I often find when the vomer itself is azygous, as in Anser palustris, 

 Psopliia crepitans, Circus cyaneus, Haliastur indus, &c. ; it is related, morphologically, 

 to the base of the cranio-facial notch, and is distinct from the centre which ossifies the 

 postero-inferior part of the septum nasi. Thus the unspecialized submucous plates seen 

 in the vomerine region of the Sturgeon reappear in their old profusion in these nobler 

 types, but are specialized to the highest degree. 



The next arch, the pterygo-palatine, has as much and as little of the Passerine type as 

 the one described. The palatines themselves are of great length (figs. 8 & 9, pa), and 

 are extremely slender, especially the distal part ; they thicken gradually to the widest 

 part, and then gently taper off to their posterior end. On the inside of the widest part 

 each bone sends forward a long interpalatine style (ipa) ; and on the outside a wart-like 

 protuberance represents the transpalatine of the " JEgithognathse." This is only seen 

 in the adult, and is a mere periosteal outgrowth (figs. 3 & 4, tpa). 



In some low-type Passerines, such as Pipra and Pachyrhamphus, the transpalatine is not 

 much larger ; in the young Humming-bird the palatines are as much deficient here as 

 those of the Hemipods. The ethmo-palatine lamina (figs. 9 & 10, epa) is very much 

 stunted, the reverse of what obtains in the Swift and Goatsucker, where it is of extreme 

 length ; and in them the vomerine crura articulate and then coalesce with these laminae, 

 whereas they remain distinct in the " TrochiUdce." The short stoutish pterygoids (pg) 

 are scooped in front, where they rest upon the end of the palatines ; in the young (fig. 10, 

 pg, mspg) the mesopterygoid piece is nearly distinct from the body of the bone; it 

 becomes quite separate, and then coalesces with the palatine. Both palatines and 

 pterygoids are faceted with cartilage to glide upon the short, stout, flat-faced basi- 

 pterygoids {bpg). Each pterygoid is sharp-edged both above and below, and above the 

 shallow cup for the pterygoid there is scarcely any epipterygoid process (epg). In this 

 these birds are contrary to the " iEgithognathse." In the young (figs. 8 & 9, mx) the 

 maxillaries are clearly traceable ; the broad flat part is about equal in length to the 

 lono- terminal spike, which is equal to that of the palatine ; already, the posterior style 

 (zygomatic process) has coalesced with the long jugal (J). The dentary edge is quite 

 overlapped by the premaxillary, opposite the end of which we see the characteristic 

 ornithic process, the " maxillo-palatine." 



These outgrowths from the maxillaries are of great interest to the morphologist ; here, 

 in the Humming-bird, they show relationship as by the most delicate test. In the young 



