484 ARKIV FÖR ZOOLOGI. BAND 1. 



backward prolongation of this rostrale along the culmen 

 niight be an enlargement of the rostrale alone, which is most 

 probable, or perhaps developed through the fusion of the same 

 with an internasal shield. Either side of the upper rhampho- 

 theca is formed by a longitudinal shield corresponding to one 

 or several fused labialia such as they are fonnd in the reptiles. 

 Behind the posterior end of the rostrale on the culmen there 

 is a median shield which partly embraces the rostrale. This 

 shield I think must be regarded as a homologon to an inter- 

 nasal or frontonasal, but the nasal region itself is soft. 



In Casuarius similar structures are found. »The rham- 

 photheca of the upper jaw is compound» as Pycraft 1 says, 

 »being composed of a small median rhino- and small lateral 

 gnathothecse». The whinotheca^ corresponds, according to my 

 opinion, with rostrale and the »gnathothecce» with labialia. 2 

 On a specimen of Casuarius galeatus I find the lower rham- 

 photheca composed of several pieces, viz. an unpaired termi- 

 nal piece = mentale, and at least two lateral pieces on either 

 side. These two shields lie not one behind the other but 

 the one covers the upper or dental margin of the jaw, the 

 other pro teets the inferior part of the mandibular ramus be- 

 low the former. This is an arrangement which is to be re- 

 found in many other birds, as will be shown låter on, and 

 I think that both these shields may be interpreted as a rep- 

 tilian inheritance as well. But this interpretation may be 

 made in two different manners concerning the lower one. The 

 upper one is, of course, a homologon to one or more infra- 

 labials, but the lower one might be taken either as an infra- 

 labial which by the stronger growth of the one just mentioned 

 has been excluded from the upper edge of the mandible or, 

 and that appears more likely, represents the lower shield a 

 submandibular. — Behind the rostrale of the upper jaw the 

 casque rises in the same place where the supposed internasal 

 or frontonasal has been described above in Bhea. The an- 

 terior edge of the casque which borders the hind-end of the 

 rostral embraces the same in quite a similar manner as the 

 mentioned shield of Rhea does, and I have no doubt in ho- 

 mologising the casque with the same. The casque is thus 



1 On the Morphologv and Phvlogeny of the Palceognathce and Neognathce. 

 Träns. Zool. Soc. Vol. XV Part/5 London 1900. 



2 There are indications of (at least) two such on either side. 



