1875.] TRACHEA OF CERTAIN DUCKS. 153 
thinned rings ; in the female (fig. 2) there are only 12 of the same. 
In the latter there is no lateral ‘diverticulum from the syrinx ; but 
in the former, from the left side, as usual, one is developed, entirely 
osseous, irregularly compressed, and very small, not having a di- 
ameter in any part greater than that of the trachea itself (vide figs. 
1 & 2). 
In as male specimen the ceca are 3 and 23 inches long; in the 
female not quite 2 inches. Their diameter is inconsiderable, not 
exceeding $ ofaninch. The whole intestinal canal measures between 
43 and 5 feet ; and the gizzard is decidedly small, not being bigger 
than that of a common Duck (Anas boschas). 
2, RHODONESSA CARYOPHYLLACEA (Lath.). 
Anas caryophyllacea, Scl. P. Z. 8. 1874, p. 110. 
This rare Duck is generally placed in the genus Anas; by Mr. 
Eyton, however, it is considered to belong to the Fuliguline; and that 
ornithologist puts it, along with Fuligula rufina, in the genus Callichen. 
A pair purchased by the Society on the 12th of January last year, 
Fig. 4. Lower part of trachea of Rhodonessa caryophyllacea 3 (front view). 
Fig. 5. Ditto (side view). 
died, the female on the 11th and the male on the 15th of March, 
1874. From these two specimens I was able to remove the windpipes 
for examination. The structure of the syrinx of the male is in favour of 
