SKULL OF THE ZGITHOGNATHOUS BIRDS. 305 
great Pluvialine group, or a rounded notch as in the Passerines and Gallinacee 
proper, is exactly intermediate, being lanceolate. It agrees very closely in 
this respect with the small Hemipodius already described by me (Trans. Zool. 
Soc. vol. v. pl. xxxiy. fig. 3). 
7. The bevelled shoulders of the vomer articulate with the maxillo-palatines, as 
in the Cotingide and Formicariide. 
8. It agrees with Hyloterpe, Pachycephala, and Cypselus in its “os uncinatum.” 
It also agrees with the Hemipods in showing part of the bony ethmoidal plate 
(fig. 5, e. eth) between the forks of the nasal, but not to the same extent—not 
as a swollen mass, but as a thin lamina, as in those birds generally that have 
the nasal notch sharp. 
Pigeons, birds that stand immediately above Sand-Grouse and Plovers, and, although 
of a higher type, are almost equally related to both those groups, have the same 
structure ’. 
The narrow frontal region between the eyes is deeply sulcate above; but the 
Gallinaceous value of this character is immediately annulled by the presence of very 
distinct super- and postorbital fosse for the nasal glands: in this thing it is contrary to 
the Fowl tribe. The structure of the interorbital space, presphenoid, orbitosphenoid, 
and pars perpendicularis (p.s, 0.s, pe) is in perfect harmony with the Gruine and Plu- 
vialine types of skull. 
But there is one thing in the relation of the lateral ethmoid to the palatine which 
corresponds with that of both the Cuculine and of certain Votogwal Passerines: a “‘ pars 
uncinata,” like a small nipple, projects forwards and outwards close in front of the feeble 
ascending ethmo-palatine spur (fig. 5, 0.u, epa). This, to one familiar with the 
development of the Batrachian skull, is most interesting; and the two converging 
points are the elements of the primordial commissure between the trabecule and the 
pterygo-palatine portion of the mandibular arch. This is the more noteworthy as 
being in unison with the huge dilated vomerine and parasphenoidal bars, and the 
distance between the pterygo-palatines. 
The relative feebleness of these bars is remarkable (fig. 1, pa, pg); but they are truly 
ornithic and quite Gruine (see also fig. 6). The extreme shortness of the pterygoids as 
compared with the palatines is almost an exaggeration of that which is normal in 
Carinate birds. But the pterygoid of Thinocorus has become less than half its original 
length by metamorphosis; it originally reached the vomer ; and the new segment (meso- 
pterygoid, ms.pg) has coalesced with the palatine. 
1 I mention this to remind the reader how near some of the “ Altrices ” are to certain ‘* Praecoces,” and as an 
apology for any attempt to trace the Passerine rhizome. 
