M. V. Lbbour 
429 
Gercaria macomae mihi (1908 a, p. 6). 
(PL XXV, fig. 11.) 
In Macovia halthica from Fenharn Flats, occurring between mantle 
and shell, not more than three in any one specimen, three out of 20 
examined contained them. The cercaria measures 0'70 mm. long. Oral 
sucker 0'22-0‘26 mm. Ventral sucker 0'06-0 07 mm. with a crenulated 
inner margin. Small pharynx, short oesophagus, intestinal caeca reaching 
not quite to the level of the centre of the ventral sucker. Excretory 
vesicle horse-shoe shaped. Testes present, ovary in front of right testis, 
oval and slightly smaller than testis. Vitellaria lie below and to right 
side of ventral sucker. 
Further life-history unknown. 
Cercaria strigata mihi (1908 a, p. 7). 
(PI. XXV, fig. 12.) 
In Tellina tenuis and Donax vittatus from Alnmouth, Northumber¬ 
land, between mantle and shell in every specimen of Tellina examined 
(about 20) and in one Donax out of a dozen. It also occurs in 3 per 
cent, of Tellina tenuis at Millport. The body spines are very conspicuous 
and stand out in ridges giving the worm a striated appearance. Length 
0’30-0’40 mm., oral sucker 0‘09 mm., ventral sucker 0'052 mm. Small 
pharynx, 0’03 mm. long, short oesophagus, intestinal caeca broad and 
almost circular, reaching a very little way beyond the anterior margin 
of the ventral sucker. Excretory vesicle lyre-shaped. Testes sometimes 
to be seen one on each side of excretory vesicle. Hind part of body 
peculiar in being slightly drawn out at the end so as to give it the 
appearance of having a short tail. Giard (1907, p. 416) regarded this 
cercaria as very probably the young of G. somateriae, I think however, 
as I have suggested in a former paper (1908 a, p. 9), that it is more 
likely to be the young form of some Gyninophallus inhabiting a bird 
other than a duck, perhaps a gull. 
