Cetacea. 2441 



tive heights of the ground where they were respectively met with. Now I have seen 

 several individuals of this species, caught within twenty miles of London, which were 

 partially white, and one in particular, all white, except the head, and of course the 

 hlack tip of the tail. And I have a very beautiful perfect ermine, which was killed on 

 the estate of my friend, Mr. Moore, at Shelsley Beauchamp, in the southern part of 

 Worcestershire, on the 10th of March, 1847. It had been repeatedly noticed for some 

 time previous to its capture, its whiteness making it a conspicuous object in the fields 

 and hedge-rows ; and the worthy proprietor of the land kindly gave particular direc- 

 tions, that if it could be killed, it should be saved for me. Accordingly it found 

 its way into my collection. The head and body are pure white, tinged with yellow on 

 the belly and inner sides of the legs; the first half of the tail is yellow, and 

 the extremity jet black. Many speculations have been formed to account for the fact, 

 that, with us, a few stoats assume the ermine in cold weather, while the far greater 

 number, in the same locality, retain their russet garb. My own opinion is, that 

 though, in cold countries, every stoat becomes an ermine, on the approach of winter, 

 yet that those which turn white, in our climate, are the very old ones, and those alone. 

 — Id. 



Note on the Physeter bidens. — Allow me to mention that your correspondent at 

 Hull, Mr. T. Thompson, is in error regarding the supposed Physeter bidens in the 

 museum of that town (Zool. 2407). Mr. Thompson has given the distinctive charac- 

 ter by which it may be pronounced to be a Hyperoodon, namely, two (procumbent co- 

 nical) teeth concealed beneath the thickened gum at the anterior extremity of the 

 lower jaw. In the male of the Physeter bidens (Delphinorhynchus micropterus), there 

 is a greatly compressed tooth placed in the alveolar groove at its commencement near 

 the middle of each ramus ; while in the female, several teeth of much smaller dimen- 

 sion, but similar in form, are arranged along the alveolar groove. A figure of the for- 

 mer may be seen in Mr. J. E. Gray's article on " Whales " in the zoological portion of 

 the Antarctic Voyage, under the name of Ziphius Sowerbei ; and of the latter in F. 

 Cuvier's volume on the Cetacea in the ' Suites a Buffou.' I have had the good fortune 

 to dissect two females of the Hyperoodon, stranded at Boness in the Firth of Forth ; 

 and Dr. Cogswell and myself saw last summer the skeleton of one in the museum of 

 the Royal Institution of Liverpool, prepared by the obliging curator, Mr. Johnstone. 

 An elaborate monograph of the anatomy of the Hyperoodon has recently been given 

 by the great Dutch naturalist Vrolick, confirmatory of the fact previously detailed by 

 our celebrated Hunter, whose preparations of this animal may be seen in the College 

 of Surgeons. There is an excellent account of one stranded near Belfast by Mr. W. 

 Thompson, the distinguished president of the Natural History and Philosophical 

 Society of Belfast, in the ' Annals of Natural History,' about four years ago, to which 

 I cannot, unfortunately, now refer. The supposed rudimentary baleen filaments have 

 no existence in the Hyperoodon, as stated in various books ; and there is in addition 

 to the two larger teeth at the front of the jaw, a series of small ones which never ad- 

 vance beyond the sacular stage, and are, perhaps, absorbed in aged individuals ; in 

 young specimens, they are removed with the gum when the latter is stripped off the 

 shallow continuous alveolar groove, as demonstrated by vertical sections, transverse or 

 longitudinal, of the gum itself. I now throw out, as a conjecture for future inquirers, 



