AND DEVELOPMENT OF THE BIRD'S SKULL. 115 



of the overgrown " transverse" region; and the first and only palatine centre runs riot 

 over both morphological territories. Also in the hinder division of the arch-moiety the 

 pterygoids correspond to those of the young nestling, but not to those of the fledgling Pas- 

 serine; for each pterygoid sends a spike-shaped process over the palatine; but this does 

 not become a " mesopterygoid " bone (Plate XXI. fig. 11, and Plate XXII. fig. 1, pg). 



The lower fore-looking spines of the palatines do not increase much in size — compare 

 the " interpalatine " of the young (Plate XXII. fig. 1, ipa) with those of the adult 

 (Plate XXI. fig. 8). But the upper or orbital processes, the ethmo-palatine bars, grow 

 exceedingly, and meet by suture at the mid line (compare Plate XXI. figs. 8, 9, & 11, 

 epa). This apposition is a step towards a true facial " commissure." The palatines are 

 elegantly bowed outwards from each other behind this tract, and then form a complete 

 commissure, like that of the trabeculse (Plate XXI. figs. 8 & 9). By the time this bird 

 is fully fledged the posterior palatal region is joined together at tbe mid line by a 

 cartilage common to both sides, and this cartilage becomes ossified by two endosteal 

 centres ; these I propose to call the anterior and posterior " medio-palatines " (Plate XXI. 

 figs. 8 & 9, mpa). Now the morphologist, at first "rounding about in darkness," feels 

 himself safely within the great Cuculine territory, knowing that there and amongst the 

 " Celeomorphous " tribes (Piciclse) this structure is alone to be found *. 



With regard to the articulation of the pterygoids with the basipterygoid processes 

 (fipg), Caprimulgus is countenanced by many types within the great Cuculine circle. 

 I see them everywhere in smaller or larger rudiments ; but they are perfect in a very 

 near relation, the Oil-bird (Steatomis) , and also ia the Trogons and Humming-birds. 



There are but two pairs of palatine splints, the maxillaries and jugo-quadrato-jugals 

 (mx,j); the latter are mere curved needles of bone ; the former are elegantly ornithic pieces, 

 with, however, characters that are peculiar to this bird. In the young (Plate XXI. 

 fig. 11, and Plate XXII. fig. 1, mx) the maxillary differs but little from that of Struthio 

 camelus (" Ostrich Skull," plate viii. fig. 2, and Huxley, " Classification of Birds," 

 p. 420, fig. 1, Mxp); for the palatal plate is rough, large, and 4-sided, and the cuneiform 

 body of the bone is very similar with its zygomatic process. In the adult, however 

 (Plate XXI. fig. 8), the change is as though the most delicate chiselling had been 

 fining it down into a very Passerine element ; the maxillo-palatine hooks especially might 

 belong to a southern Crow. The bone has its own caprimulgine diagnostic in an 

 f-shaped fore-turned spur, which is applied, for defence, to the nasal wall on each side 

 (Plate XXI. fig. 10, np.mx). The figures show how thoroughly non-passerine is the 

 nasal labyrinth (Plate XXI. figs. 10 & 11, and Plate XXII. fig. 1, aln, als, atb, itb) ; 

 the upper view (fig. 11) shows, through the transparent tubular nostril-walls, the ali- 

 nasal turbinal (atb), which is exposed in the inferior view of the younger specimen. ' The 

 inferior turbinal (itb) is similarly displayed in the two figures, its line of insertion being 

 seen from above, and its anterior half is shown in the lower view (Plate XXII. fig. 1, itb). 

 I have already described the relation of the nasal wall to the vomer, and have only to 



* I am well aware that in the larger Grallse, Mycteria, Balceniceps, Ciconia, &c, and the " Totipalmatse," the 

 palatine's form a hony " commissure ;" but there is no key-stone in their palate. In the Pelicans this common bar 

 sends upwards a crest which is the symmorph of the trabecular crest. 



SECOND SERIES. — ZOOLOGY, VOL. I. B, 



