162 ME. W. K. PAEKER ON THE STEUCTURE AND 



accurately, the groove being in the " rostrum " and the tongue on the " septum ;" and then 

 these became strongly undergirt by the bony semicylindrical vomer. Moreover, behind the 

 vomer, the middle (sphenoidal) balk grows out on each side in the form of strong spurs, 

 which stretch across to the pterygoid like a roof-collar or wind-beam. This very safe 

 kind of building is best seen in these " Struthionidse," for in other birds the cross-bars, 

 or the lower beam, or both, may be deficient ; the vomer being very variable, and the 

 anterior pterygoid processes soon becoming arrested in many genera and families. 



In this Cassowary we see but a poor remnant of the second prestomal splints, the 

 inner pair being absent, the first outer pair mere flattened styles — the jugals (Plate 

 XIV. figs. 1, 2, 3, y.); whilst the second, the quadrato-jugals {q.j-), are very small 

 addenda to the jugals, just serving to connect the zygomata to the quadrate bones. 

 Moreover, as we have seen, these splints are thrust away from their early-ossifying pri- 

 mordial bars by the intrusion of the huge middle splints (prevomers) of the first prestomal 

 arcade. 



The squamosals of the Struthionidse all speak one language, but in none are the 

 utterances so distinct as in the case of the Cassowary. If the reader will refer to Pro- 

 fessor Huxley's new work on Anatomy, and compare fig. 65, Pr.Op. p. 162, fig. 84, F. 

 p. 208, and fig. 86, C.z. p. 214, with the squamosal of the young Mooruk, he will see 

 at one glance a complete harmony of the " preoperculum " of the Fish, the temporal 

 " operculum " of the Lepidosiren, the " temporo-mastoid" of the Frog, and the squamosal 

 of the air-breathing Vertebrata. As to the Frog and the Mooruk, the shape of the bone 

 has merely to vary from that of a hammer to that of a hatchet, and the oneness is abso- 

 lute. But it is not on the accident of shape that I would rely to prove this identification, 

 but on the history of the development of the bone, viz., as a splint upon the quadrate 

 pedicel of the mandibular ray, whether that pedicel be segmented from the periotic 

 capsule and " investing mass," or whether it be continuous with it*. 



The mandibular splints have their usual development, the dentary (Plate XIV. 

 fig. 1, d.) being the longest, and the splenial the next in size, then the surangular (s.o.), 

 whilst the angular («.) and the coronoid are nearly of the same size. The pinched face 

 of the Cassowary makes the mandibles to be much like those of the Tinamou, the rami 

 meeting at a very acute angle, and the dentaries being narrow feeble bones. If these 

 mandibular splints were during growth to become as free of the primary ray as those of 

 the palato-maxillary region, we should have essentially what occurs in the inner and 

 outer splints of the huge hyoid arches of the osseous fish. 



I have studied the structure of the skull in the adult condition both of the common 

 species [H. galeatus) and also of the Mooruk (C. Bennettii), but my space will not serve 

 to trace the changes, which are similar to those that take place in the other " Struthio- 

 nidse ; " the description above given of the chick will serve the student as a guide in his 

 interpretation of the fully developed skull. 



* The supposed " squamosal" of the Fish does not stand in the way now (see Htjxlet, op. cit. p. 188). 

 Ctjvier and Owejj made the nearest guess as to its nature. 



