HERODIONES 429 



at their sternal insertion in Leptoptilus.^ The hypoclei- 

 dium articulates with carina sterni. The skull is desmogna- 

 thous, holorhinal, and without basipterygoid processes ; there 

 are in Tantalus rudiments of these processes in the shape of 

 a nainute spine. The holorhinal character of the nostrils is 

 largely marked by ossifications of the alinasals ; the nostrils 

 are thus much reduced in size, in a fashion suggestive of the 

 Steganopodes and possibly significant, but there is no bony 

 septum between them. This distinguishes the storks from 

 the herons, as does also the forin of the palatines. These 

 bones are in the first place not cut off at right angles behind, 

 as in the herons, while the internal lamina only bounds the 

 interparietal space, and is at most (Xenorhynchus) carried 

 back to the end of the bones as a slight median keel. This 

 is absent in other storks. In Xenorhynchus and Leptoptilus 

 the palatines again approach each other, and are only sepa- 

 rated by the vomers just behind the maxillo-palatines. Oppo- 

 site to this point each palatine is produced into a strong 

 outwardly directed snag, large in Xenorhynchus, hardly indi- 

 cated in other storks. The interorbital septum is entire. 

 The large lacrymal is perforated or deeply notched for duct 

 of gland. 



Family Ardeidae. — The herons contrast with the storks in 

 (1) the tracheo-bronchial syrinx always furnished with a 

 pair of intrinsic muscles, (2) non-division oipectoralis primus 

 into two layers, (3) invariable absence of ambiens, (4) pre- 

 sence of powder-down- patches, (6) absence or weakness of 

 vinculum, (6) presence of a single caecum only. 



On the other hand the two families agree in (1) absence 

 of biceps slip to patagium, (2) presence of expansor secun- 

 dariorum, in addition, of course, to the points enumerated in 

 the definition of the group. 



In Gancroma the oil gland is nude. The herons have 

 four or six powder-down tracts. Six are found in Gancroma, 

 Butorides . atricapillus, Ardea cocoi, and other species ; 



' Not in Xenorhynchus and Dissura ; there is a trace of an overlap in 

 Abdimiat Tanialus,- and Platalea. 



