OSTEOLOGY 149 



universally retained than in other birds. As T. J. PARKED 

 has shown in Mesopteryx, Anomalopteryx, and (according to 

 OWEN) Dinorni-s torosus, and finally in the young of Emeus 

 crassus, there are distinct paired voiners. The strong anterior 

 and posterior bifurcation of the voiner in living Struthionidse 

 is an indication of the partial fusion of the primitively 

 separate halves of the single vomer. A double vomer, 

 however, is not a feature of the struthious birds alone; in 

 the young Hesperonu's the same occurs ; in the woodpeckers 

 (hence Saurognathse in PARKER'S nomenclature) there are two 

 distinct vomers, while PARKER has recently committed him- 

 self to the general statement that ' in most birds that have 

 a large or wide vomer it is double at first.' The inference 

 is that the single thread-like vomer of many birds is in a 

 degenerate condition. In any case a large vomer, double or 

 single, and a lacertilian palate generally mark all the stru- 

 thious birds, and justify their generally recognised position 

 somewhere not far from the root of the avian series. 



As for desmognathism and schizognathism, Professor 

 PARKER has aptly remarked : ' The use of such a taxonomic 

 character as desmognathism or schizognathism is very 

 extensive in some groups and very limited in others ; and 

 there is no sharp line of demarcation between the two. The 

 most lacertilian palate for openness is that of the woodpecker ; 

 the most modified by intense ossification is that of the 

 toucan ; yet these two types, each specialised to the utter- 

 most, have a postcephalic skeleton, not indeed identical, but 

 extremely similar.' 



That the toucans and woodpeckers are exceedingly near 

 akin is also shown by many other features of their organisa- 

 tion (see below). HUXLEY claimed for his Schizognathse 

 that they were a natural group, but hardly claimed so much 

 for the Desmognathfe. He admitted, however, that Cariama, 

 a schizognathous bird in the totality of its organisation, had 

 a palate approximating to the desmognathous. The Cracidae 

 and Rhinochetus are in the same anomalous position. The 

 Trogonidse, whose nearest allies are the desmognathous 

 birds, have a schizognathous palate (as was pointed out by 



