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Show 158 DR. H. LYSTER JAMESON ON THE [Mar. 4, and rediscovered by me in the Scoter, (Edemia nigra L., from Bridlington Bay and the Villaine Estuary. After finding the Sporocyst I made a careful examination of such fishes and gulls as I could secure at Billiers, but could find no parasite corresponding to the larva. However, on enquiring of the fishermen I was informed that the great enemy of the mussel in those waters is a diving duck, locally called " Cane mouliere," which frequents the Villaine in winter. M. d'Hamonville, to w h o m I wrote on the matter, had no hesitation in saying that this bird was OjJdemia nigra. On my visit to Billiers in December last I proved, by shooting an example and procuring four others that were taken in nets, that it was so. The name " Cane mouliere " seems to be applied to another duck as well, probably the Scaup, Fuligula rnarila Linn. A few young Scoters remain on the Villaine during the summer months. The Scoter is very common in winter at the mouth of the Barrow Channel, just opposite the pearl-bearing mussel-beds. Before going to Billiers in December I had proved the occurrence of L. somaterioe (Levinsen), associated with Levinsenia pygmceum Lev., in a specimen of (Edemia nigra sent m e from Bridlington by Mr. G. Williamson. The Scoter received from Bridlington was in a rather advanced state, and I could only determine the presence of a few examples of L. somaterioe in the hinder part of the small intestine. But the five specimens procured on the Villaine were infested with L. somaterke from the stomach to the anus and even in the caeca. I calculated that each specimen contained at least six thousand examples of the parasite. Levinsenia pygmceum Linn., which occurred abundantly in the Bridlington specimen, was not found at Billiers. The intestine of the Bridlington duck contained nothing but fragments of Mytilus-sheUs. The example which I shot at Billiers was feeding over mussel-beds, and the other four were caught in special nets which are placed on the beds of mussels at ebb tide, and in which the birds get entangled when they visit these beds with the flood, to feed. These Billiers specimens had apparently been feeding exclusively on mussels, as no other food was found in them, except that one individual contained about half a dozen Nucula sp. and a broken Littorina-shell, in addition to Mytilus. In the crop and stomach some of the mussels were still entire, and specimens up to 40 millim. in length were found ; in the stomach the shells are crushed, and pass through the intestine in small fragments at most a few millimetres in diameter. The striking likeness, except for the matter of size, between the Mytilus-worm and Leucithodendrium somaterioe, and the occurrence of the latter in the two birds that are known to feed par excellence on mussels, is almost sufficient to prove their identity without the feeding experiment. I hope, however, to make this experiment if birds can be secured. So far I have been unable to purchase live examples, although I have made enquiries |
