DEVELOPMENT OF THE SKULL EST THE OSTRICH TEIBE. 155 



This is a remnant of that extensive space in the Lacertian skull which extends from 

 the Y-shaped orbito-sphenoid to the margin of the prootic, and which is somewhat 

 defended by an upgrowing rod (" columella " of Cuvier) of the pterygo-palatine arcade. 

 The whole of the anterior sphenoid (Plate XIV. tig. 1, o.s. p.s.) is still mere cartilage, 

 and the wings, about 3 lines in extent, are only a line broad (Plate X. fig. 20, o.s.); late- 

 ness in ossification and stunted growth are, as usual, here associated. The interorbital 

 " fenestra" (Plate XIV. fig. 1) is oval ; the long diameter vertical, and it is 3^ lines by 2 

 in size; a full "line" of cartilage intervenes between it and the perpendicular ethmoid 

 {p.e.). The continuous interorbital septum is very large, the orbit being 9 lines in dia- 

 meter ; thus the ethmoidal region is very large indeed, reaching behind over and below 

 the whole fenestra, and in front taking in, without a notch or a change of tissue, all the 

 way between the turbinals and the alee nasi. Then it is not merely the height of the 

 perpendicular ethmoid which gives it its great size, but the upper piece in this group of 

 " Struthionidae" takes on a monstrous growth. In all the members of the Struthioua 

 family the mode of ossification (by an upper and a lower centre) is peculiar ; and so is 

 the persistent exposure of the crovra of the cranio-facial axis : this is normal in osseous 

 Fishes ; but in them, as in typical birds, the perpendicular bone reaches through to the 

 top, and is not capped by a second piece. 



It is the overgrowth of this upper piece (Plates X. & XIV. eth.) which gives the 

 Cassowaries their great peculiarity ; for in them it not merely appears at the surface, 

 but it emerges, like the intrusion of a hypogene rock through the secondary strata of 

 the earth's crust, leaving the frontals and lacrymals merely flanking its sides (Plate X. 

 figs. 18 & 20, & Plate XIV. figs. 1, 3, 4, & 8). This is not like the account which is 

 given of the Cassowary's crest in the Osteological Catalogue of the Museum of the Col- 

 lege of Surgeons (vol. i. p. 259, No. 1356); but the distinguished author of that Cata- 

 logue had evidently not been so fortunate as to obtain the head of a Cassowary chick. 

 I had compared the Ostriches to the Sharks and Rays long before I saw the meaning of 

 the Cassowary's crest, but this huge swelling upgrowth of the anterior part of the pri- 

 mordial skull carries the mind back to the same part of the organization of the lower 

 plagiostomes, e. g. Chimcera and Callorhjnchus. 



The crest of the adult Mooruk (C Bennettii) has three thick convex ridges meeting 

 at the top — one in a line with the axis of the skull, and the two others out-turned like 

 the horns of the coalesced parietal bone in Lizards (see the excellent figure given in 

 Dr. Sclateb's paper on the " Struthionidae," Trans. Zool. Soc. vol. iv. pi. 72). This 

 curious ethmoidal horn-core, with its leaden-black horny sheath, is a pretty exact minia- 

 ture of that strange old three-wayed bridge which may be seen in the small but extremely 

 ancient town of Crowland, in the Fens of Lincolnshire. 



At this early period there is no mark of the high three-rayed ridge ; for the whole 

 upper surface (Plate XIV. fig. 3, eth.), which has a lanceolate outline, is smoothly con- 

 vex; but it is already a full "line" higher than the bones that flank it (Plate XIV. 

 fig. 1.). If we turn to the figure of Casuarius licarunculatus {op. cit. pi. 73), we shaljl 



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