102 Miss yU V. Lcbour on 



IX. — Ou Three Molhislc-infrsting Trenmtodes. By Mai?IE V. 

 I.KROUK, B.Sc, Armstrong College, Newcastle-upoii- 

 Tjno. 



[riates VII. .^ VIII.] 



Muddy and ?anc1y flats wl.icli are left uncovered by tlie tide 

 for several hours of the day and are the haunts of nunierous 

 pea-l>irds are .'jpccialh' good ground for larval Treniatodes and 

 the moUusks and other invertebrates which harlxmr these 

 Mornis. Fenhani Flats, the land bet>veen Holy I.-latid and 

 the mainland of Northumberland, is one of these good localities, 

 and the shore of Loch Ryan, at Stranraer, in Galloway, is 

 another. TCnmerous Treniatodes are to be found in both 

 places, three of which seem to be specially worthy of attention 

 and are here described. 



'i'he greater part of the flats near Holy I.'ilnnd is uncovered 

 for several hours each day, but the Mussel Scaup, which lies 

 to the south-west, remaijis almo.'it completely covered except 

 at spring-tides. Here the ground is more gravelly and many 

 mollusks abound. Cockles are fairly numerous, but perha])3 

 the commoiie.-it shell is the little white whelk Purpura 

 lapillus, which preys continually on the mussels and is found 

 in clusters all over the scaup. It is, however, a very small 

 form. 



The shores of Loch Ryan at Stranraer are chiefly made 

 up of muddy sand, with large stones strewn about, and the 

 tide leaves a long stretch of ground uncovered for several 

 Lours each di.y. The usual couimon mollusks are found. 

 Purpura lapillus being particularly large and fine. 



Tlie Treniatodes to wjiich 1 should like to draw attention 

 are all species of JJistomum. The first infests the cockle, 

 Cardium edule, and was noticed some time ago in one cockle 

 out of many examined from Budle Bay, Northumberland, 

 and was imperfectly described and figured by me {' North- 

 umberland Fisheries Report' for 19<'5, p. 100, |)1. ii. fig. 3). 



Mr. James Johnstone, of the Liverpool Fisheries Labora- 

 tory, si-nt me another s])ecimeu of the cockle infested with 

 this parasite from Yeoman Wharf, Morecambe Bay, and kindly 

 allows me to use his drawing of the living si'Orocysts 

 (PI. VII. A). In October J 90G I again found this Trematode 

 in a cockle from the .Mu.-^sel Scaup, Holy Island, and am now 

 able to descnbe it more in detail. I'he visceral mass of the 

 cockle, which is whitish and unhealthy-looking, is almost 

 comjdt'tely riddled v.ith sporocysts, especially where the 



