420 Mr. H. Seebohm on the 



he at first supposed it to possess, inasmuch as some birds are 

 intermediate. The character consists of two parts, one relat- 

 ing to the length of the nasal aperture, the other to its shape. 

 Some genera, of which Cursorius and Glareola are examples, 

 are schizorhinal in respect of the length of the nasal aper- 

 ture, but holorhinal in respect of its shape. These birds were 

 regarded by Garrod as schizorhinal. 



This character appears to be constant in Columbse, Ptero- 

 cletes, Crypturi, Gallinae, Podicipes, Colymbi, Tubinares, and 

 Impennes, but it breaks down in the Gavise and the Grallse. 



The typical Gruida are schizorhinal, but the Rallidae are 

 holorhinal. The typical Gruidse have a long narrow sternum 

 with no xiphoid processes ; but the Rallidse have long external 

 xiphoid processes, separated by a deep notch from the median 

 xiphoid process, and considerably prolonged beyond it. The 

 genus Psophia is Ralline in the bifurcation of the nasals, but 

 Gruine in the shape of its sternum. It is also Gruine and 

 not Ralline in the extent to which its dorsal vertebrse are 

 aiikylosed ; but it is Ralline, and not Gruine, in having, when 

 adult, no lateral occipital fontanelles. 



Lateral Occipital Fontanelles. 



In addition to the foramen magnum many birds have 

 lateral fontanelles in the occipital bone. It is not known 

 that these lateral fontanelles serve any special purpose, unless 

 economy of bone be regarded as such ; but in some cases 

 they are very useful as aids to classification. For ex- 

 ample, they are present in the Charadriidse and absent in 

 the Parridse, which otherwise agree in being schizorhinal 

 and in having basipterygoid processes. They are pre- 

 sent in the Alcidse and absent in the adult Laridse, which 

 also agree in being schizorhinal, but are without basiptery- 

 goid processes. 



But, like all other osteological characters, the presence or 

 absence of lateral occipital fontanelles is a most unsafe guide 

 to the classification of birds. Although they are normally 

 present in the Charadriidse, they are frequently completely 

 ossified, in some species [Totanus pugnax, for example) more 



