SKULL OF THE ^GITHOGNATHOUS BIRDS. 283 



is similar to that of Suthora ; but the right and left keels come nearer together, leaving 

 a narrow postnarial passage ; they have not so steep a posterior edge, which is gently 

 concave or emarginate: the diflFerence here is very slight between the lesser and larger 

 skulls. The transpalatine region (t.pa) is equally steep and strong ; the snags them- 

 selves are more dilated and round at the end. 



The ethmopalatal lamina (figs. 5 & 6, e.pa) is of greater extent than the interpala- 

 tine (i.pa), and not merely equal as in Suthora and Parus ; it ascends very high, and 

 is a large half-coil, as in many of the Passerines of South America. The interpalatine 

 snags are thick and spongy. The prsepalatine bar {pr.pa) is large and lathy, wider 

 behind than it seems from below, because twisted on itself; at the middle, as in 

 Suthora, it widens sensibly, and then narrows a little towards the fore end, so as to 

 expose the alinasal turbinals {a. tb) ; it is completely ankylosed to the rostrum. Thus 

 the palatines differ more in " letter " than in '• spii-it " from those of Suthora, and not 

 otherwise than the rest of the skull differs. 



The cranio-facial hinge exists here only in virtue of the elasticity of the bones; 

 for the nasals and nasal processes of the prgemaxillaries pass, by ankylosis, directly 

 into the frontals ; and the maxillaries, laterally, pass insensibly into the rostrum {mx, 

 d.px). Thus we miss that parrot-like mobility of the face, and are, consequently, on 

 the outer border of the Tit family. The fore part of the roof of the rostrum is deeply 

 grooved in a rounded manner ; and this groove ends in a triangular tongue of bone as 

 in Parus; the "recurrent" processes are not distinct from this flap. 



Whilst in Parus the palatal processes of the prsemaxillaries are almost absorbed (fig. 1, 

 p.px), in Cyclorhis as in Suthora they have lost all their distmctness, both from the 

 dentary edge and from the prjepalatine bar (fig. b, p.px, d.px, pr.pa). The maxil- 

 lary widens as it passes into the jugal bar {j), which is of moderate strength. The 

 maxillopalatine processes (mx.p) have a short, straight, flat pedicle, which is as broad 

 at its root as at the dilated end. That end is swollen, pneumatic, and just like that 

 of a Tit. 



The vomer (v) is large ; but its crura converge, and are completely ankylosed to the 

 shelly ethmo-palatines. The emargination in front is wider and straighter than in 

 Suthora, and its crura somewhat shorter; but they are extremely alike. The " horns " 

 of the vomer pass insensibly, by bony substance, into the large alinasal turbinals, 

 which are well ossified and, as in Suthora, show through the short round nostril (figs. 

 5 & 6, a. tb). As in Suthora, the septomaxillaries do not keep distinct. The septum 

 nasi (fig. 5, s.n) is a very remarkable mass of cavernous bone; it is completely ossified, 

 not merely calcified ; and the nerve-bridges are seen as the side-walls of a large air- 

 cavity, which runs forwards along the mid line, above the lower face of the alinasal 

 turbinals. Looking through the chink between these scrolls Ave can see that the whole 

 septum is hollowed from below, the ossified trabecular flaps forming the shelving roof 

 of the long air-chamber. 



VOL. X. — PART VI. No. 5. — June 1st. 1878. 2 b 



