REPORT ON THE ANATOMY .OF THE PETRELS. 33 
last tracheal rings, forming together the framework of the lower larynx. In most cases 
the last tracheal ring bears a well-marked antero-posterior pessular bar. 
It is in the genus Pelecanoides (figs. 3, 4) that the typical construction of the syrinx 
Fic, 3.—Syrinx of Pelecanoides wrinatrix, from before.* Fic. 4.—The same, from behind. 
of the Tubinares is seen in its simplest form ; it will, therefore, be described first on the 
present occasion. 
The last tracheal ring is complete in front, and not modified in shape; posteriorly it 
is produced downwards into a well-developed pessulus, so forming a complete three-way 
piece. The first bronchial semi-rings are united in front, where they are produced 
triangularly downwards ; behind, their inturned ends do not unite either with each other 
or with the pessulus, or with the second semi-rings. These last, as well as the third, 
fourth, and fifth, on which is inserted the muscle, are all similar in shape, and separate 
from each other; they are closely approximated in front, gradually getting shorter 
posteriorly. 
Garrodia, which may be considered typical of the Oceanitidee, is anteriorly (fig. 5) 
Fic. 5.—Syrinx of Garrodia nerets, from before. Fic. 6.—The same, from behind. 
a. The last tracheal ring, from below, to show the pessular bar. 
almost the same as Pelecanoides, but the first, second, and third bronchial rings are 
complete (fig. 6). The last tracheal ring bears a complete pessulus (5, ). 
1 This and the succeeding figures of the syrinx of the Tubinares have been drawn as nearly as possible of one 
uniform size, irrespective of that of the originals, and are also slightly diagramatic. The bronchial rings are numbered 
from 1-5 ; the tracheal are marked 0, 00, 000, &c., in the reverse direction. 
(ZOOL. CHALL. EXP.—PART XI.—1882.) Li 
