TREMATODES OF THE NORTHUMBERLAND COAST 35 



A long and narrow oesophagus runs to about half way down 

 the body, and there branches into two short lobes. Between 

 these lobes and slightly in front of their termination is the 

 small ventral sucker, 0-023 mm. across. 



This Spelotrema does not appear to fit in with any known 

 species. 



Cercaria balani, nov. (Plate I. fig. 6, 7.) This species 

 occurs encysted in the common barnacle, Balanus balanoides, 

 which encrusts the rocks and mussels at Budle and Fenham 

 Flats. The cyst is thin-walled and spherical, measuring 

 0-04 mm. in diameter. In it is curled up a pale yellow cercaria 

 measuring, when extended, about i mm. in length. Unfortu- 

 nately measurements of the organs were not made and the 

 specimens were preserved badly, so that at present they cannot 

 be determined. The size of this species suggests its being 

 the larval stage of Spelotrema excelle/is, Nicoll* which lives in 

 the Herring Gull Larus a?-genfaftis, and this would be a very 

 likely host for the worm, as the Herring Gull is one of the 

 common feeders on the coast. It, however, differs from 

 Spelot7'ema excellens in the position of the pharynx, which is 

 situated nearer the intestinal lobes than the oral sucker, thus 

 giving great length to the prepharynx. The intestinal lobes 

 extend slightly beyond the ventral sucker. The body is 

 covered with small spines. 



Cercaria carcini, nov. (Plate I., fig. 8-9). This cercaria 

 occurred encysted in Caixmus nmnas, the common green crab 

 of our coast. When pressed out of the cyst it corresponds in 

 almost every way with the worm from the same crab described 

 by Mclntoshf. It is 0*54 mm. long, its smallest breadth 

 being in the centre of the body. The suckers are almost 

 equal. The oesophagus is more than twice the length of the 

 prepharynx, and the intestinal lobes reach to the level of the 

 anterior margin of the ventral sucker. Two round bodies, 



* Mcoll, W., Op. cit.. Ann. and Mag. Nat. Hist., Ser. 7, Vol. XX., 1907, p. 248. 



t Mcintosh, " The Trematode Larva and Asoaris of the Carcinus mceii.as," Journal 

 of Microscopical Science, Vol. V., N.S., 1865, p. 201. 



