ANATOMY OF THE SHOE-BILL. 691 



and Scopus the nasals break the transverse line of the hinge, 

 fitting into the frontals. 



The anterior tip of the premaxilla is proiluced in Bcdceniceps 

 to form the strong down-turned hook of the bill. Scopus repeats 

 this on a smaller scale ; in Cancroma the sharp point is not bent 

 into a hook. In the other Herons and in Storks it is straight. 



Palate. — The palate is desmognathons in Jjalcenicejjs, the 

 maxillo-palatines being fused in the middle line, and the vomer 

 represented by a triangular, very thin, ossification, the knife-like 

 base of which divides the internal nares when seen from below. 

 The condition in Scopios is almost identical, but at its proximal 

 end, where it touches the central laminfe of the palatine, the 

 rather larger vomer shows a broader edge with the faintest 

 suspicion of doubling. In the Storks, the vomer is relatively 

 smaller even than in Balceniceps and there is no ti'ace of forking. 

 In Cancroma and Ardea the vomer is relatively very much lai'ger 

 and its edge is quite distinctly cleft between the palatines, each 

 blade being attached to the palatine lamina contiguous with it. 

 In this respect Balceniceps and the Herons ai'e at the opposite 

 ends of the series. With regard to the palatines, the most 

 striking featui-e in Balceniceps^ f'^-^ll}'^ described by Parker, is the 

 coalescence of the internal laminge to form a strong keel sti'etch- 

 ing back from the posterior nares to the pterygoid articulations. 

 Allowiiig for difterences in shape and proportion, the similarity 

 with 6'copus is close. The median keel is still more sti'ongly 

 marked in the Pelican and in Flotus ; it is represented in Storks 

 by a delicate median ridge, but in Cancroma and Ardea the 

 internal laminfe of the palatines remain completely separate. 



Pterygoids. — I notice no significant difierences between the 

 pterygoids of Balceniceps and those of Scoptis, Storks and Herons. 

 Basipterj'goid articular processes are absent in all, and I have 

 not found even any rudimentary trace such as is common in the 

 Pelican. The ventral distal end of each pterygoid is smoothly 

 rounded in Balceniceps and Ardea ; in Cancroma, Scopus and 

 most of the Storks it sliows a sharp keel running out as if to 

 meet the outer lamina of the palatal. 



Quadrate. — This is substantially alike in Bcdceniceps. Scopus, 

 Herons and Storks, but the orbital process in Balceniceps is aJmost 

 triangular, the blunted apex j)i'ojecting into the orbital caviiy. 

 In Scopus the orbital process is luther blunter ; in Tantalus moi'e 

 acute, but in Storks generally it tends to expand to a spatulate 

 end, and in the Herons, including Cancroma, the apex is much 

 expanded. 



Quadratojugal bar. — This is enormously stout in Balceniceps, 

 and the separate portions of which it is composed cannot be dis- 

 tinguished. In all the other birds I am considering, it forms a 

 slender, much elongated rod. 



Temporcd cavity. — The boundaries of the temporal cavity 

 present interesting modifications in Bcdceniceps and its allies. 



Puoc. ZooL. Soc— 1913. Xo. XLYI. 46 



