1896. ] MR. R. LYDEKKER ON THE SEA-OTTER. 235 
Nycticorax griseus may serve as a typical Heron upon which to 
hang the description of such slight divergences from the normal 
as exist. Reckoning as the last tracheal ring that from which the 
pessulus arises in front, the intrinsic muscles, which are narrow 
and do not fan out much, are attacbed to the third bronchial 
semiring ; on the posterior aspect of the syrinx the last tracheal 
ring is incomplete, the pessulus being attached to the one in front. 
The widest bronchial semirings (seen laterally) are the third and 
fourth ; they are also the last ossified ones. I can detect no differ- 
ence in Ardea cinerea, A. cocoi, A. agami, A. candidissima, Nycti- 
corax violaceus, and Tigrisoma brasiliense. In Ardea ludoviciana 
each muscle is much fanned out and almost divided into two 
muscles, of which one is inserted near to hinder border of rings. 
6. ‘Additional Note on the Sea-Otter. 
By R. Lypexxer, F.R.S. 
[Received January 10, 1896.] 
In reference to my note on the Sea-Otter (Zataw lutris), published 
in the Society’s Proceedings for 1895 (p. 421), I have received 
another communication from my correspondent Mr. H. J. Snow, 
of Yokohama. He therein tells me that I have misunderstood the 
Sea-Otter in walking posture. 
meaning of his statement that “the hind flippers are doubled 
back.” In interpreting this as meaning that they were bent 
