SlUKKI.DT : OSTF.Ol.OGY OF ril|-, I I l.kODK )NKS. 105 



with e(iual exactness tor the same depressions as found in Ariica can- 

 didissinux, a specimen of which [ have before me. \\\ the Vellow- 

 Crowned Night Heron, their forms differ materially, (Fig. 29), as 

 well as their position. ^Ve observe in this species that these depres- 

 sions are separated from each other in the median line by (juite a 

 broad isthmus, w'hich meets the apex of the supra-occipital line. The 

 region below this latter, presents a prominent, though rounded 

 median crest. In the Night Heron, (tV. violaceiis'), too, it can be 

 said, that they are more on the posterior aspect of the skull, than 

 on top. This fact is better appreciateci by comparing the lateral as- 

 pects of the skulls of the two birds. (Figs, i and 28.) 



I omitted to point out in passing the difference between the Blue 

 Heron and Nxcticorax violaceus in so far as the cranio- facial region is 

 concerned, as seen upon this view. Referring to Fig. 3, we will see 

 that the transverse depression described for the Blue Heron is not present 

 in the Yellow-Crowned Heron, the region in the latter being occupied 

 by a shallow concavity. The articulation is (juite free, however, in 

 the dried skull, and the relations of the mesethmoid are about the same 

 as in the Blue Heron. 



The skeleton of N'ycticorax violaceus that I am using, is not that of 

 an adult bird — it being "a bird of the year," which I collected at 

 New Orleans, Louisiana, in July, 1883. But since this description was 

 written I have come into possession of several skeletons of adults, and 

 upon examination of them 1 find they fall within the account here 

 given of the osteology of this species. 



Upon a lateral view- of the skull of the Blue Heron, the venated mark- 

 ings of the superior mandible become more evident, and the line lead- 

 ing forward from the anterior point of the nostril, is distinctly seen. 

 As we would naturally be led to exj)ect, the inferior and outer border 

 of this mandible is a sharp cutting edge, from the point when it com- 

 mences by the maxillary, all the way to the apex, and the bill as a 

 whole tapers gradually from its base to this latter point. 



The outline of the nostril is semi-elliptical, with a broad shelf of 

 bone extending inwards from its lower margin, and becoming con- 

 tinuous with the general outside surface of the mandible, anteriorly. 

 This shelf does not meet the fellow of the opposite side, as it very 

 nearly does in the Yellow-crowned Night Heron. Behind, these 

 shelves of bone are directly continuous with the maxillo-palatines. 

 Above them, no nasal septum is present, and an aperture exists to the 



