Moltusks. 943 



largest, an old male, weighed only ten pounds, which is considerably less than the 

 hooper. Its trachea was in what Mr. Yarrell calls the second stage, when the convo- 

 lution at the end of the sternum is on one side. The second, a female, had what, 

 according to the above-named gentleman, is the most perfect form of the trachea, 

 videlicet the loop being equal on both sides ; but I am inclined to think that the 

 former was the elder bird, for the following reasons. First, that the breast-bone of the 

 male is much more discoloured than that of the female, though the latter is far from 

 white. Secondly, that the trachea of the former fills up the cavity of the sternum 

 much more perfectly than that of the latter, so closely, indeed, as to render it ex- 

 tremely difficult to avoid rupturing it, when laying open the cavity. The third was a 

 young bird, the sex I did not ascertain ; it was in pure white plumage, but the loop of 

 the trachea was not more than an inch and a half from the anterior edge of the 

 sternum. These birds were all in very perfect plumage. The others have, I believe, 

 been purchased for the Museum of the Cambridge Philosophical Society. The three 

 that I prepared were those killed at Somersham. — H. T. Frere ; Cambridge, 

 March 17, 1845 



Enquiry respecting a species of Duck . A subscriber to 'The Zoologist,' who is 

 much interested, but not deeply versed in the history of birds, cannot satisfy himself 

 from any books in his possession, respecting a species of duck, which is sold in the 

 menageries in London, under the name of the call, or decoy duck. He lately saw a 

 number of these birds at Mr. Baker's, Beaufort-street, King's-road, which varied in 

 colour, and were as domestic as the common farm-yard duck, but not more than half 

 the size. He has a pair of them in his possession, which are even more tame and 

 familiar than the common ducks bred in his yard, and much more interesting in 

 manner. They associate with them, but the drake pays attention only to his own 

 mate. If he can be informed, through the medium of ' The Zoologist,' or the kind- 

 ness of its Editor, of the proper name and the history of the species, he will be much 

 obliged. — Rev. J. Hewgill ; Wollerton, near Nottingham, Feb. 12, 1845. 



Carnivorous propensity of the Helicidce. One or two examples having been ad- 

 duced in your pages (Zool. 201, 396), of the carnivorous propensity of snails, it may be 

 satisfactory to the gentlemen who brought them forward to find their observations 

 borne out by an instance so remarkable as the following. Happening in January 

 last to be on the Sussex coast, I captured several species of the genus Helix, adhering 

 to the underside of a log of wood, on the beach at Bulverhithe, near Hastings. 

 Having nothing in my pocket at the time but an entomological bottle, containing, at 

 least, three dozen specimens of Coleoptera, collected the previous day from the moss, 

 I put them in with the rest, and thought no more about it. On arriving at Cambridge, 

 a fortnight afterwards, I was surprised to find the snails perfectly lively, but of the 

 Coleoptera not so much as a vestige remaining, save one solitary (and dead) specimen of 

 Ptomophagus velox, which I captured in the same locality as the snails. I believe it is 

 a well known fact, that, although vegetables are the legitimate food of the Helicidae, the 

 habits of some of them (as is the case with most of the inoperculated species of Gray's 

 order " Pneumonibranchiata") are occasionally carnivorous, so that, were all vegetables 

 removed from their reach, it could be no matter of surprise to find that, as a last resource, 

 they should seize upon whatever came first to hand. But with the specimens in question, 



