24 On the Entozoa of British Marine Fishes. 



comparatively short, not exteiitling further forward than the 

 nuilcUe of the posterior testis. Its structure docs not appear 

 to difier from that in the other species of tlie genus. 



The ovary is situated a little in front of the anterior testis 

 and almost on a level with the posterior sucker or even 

 slightly in front of it. It is about the same size as each testis 

 and is round or somewhat oval. The yolk-glands consist of 

 two separate lateral groups of follicles, extending from the 

 posterior sucker halfway towards the anterior sucker or a 

 little further forwards. The yolk-ducts run down on each 

 side and unite just behind the posterior sucker. The uterus 

 is very extensive, occupying the greater part of the body 

 from a short distance behind the anterior sucker. The ova 

 are extremely numerous and for the most part of a rich 

 brownish-yellow colour ; they are regularly ovoid and of 

 surprisingly uniform size, measuring "OSo-'OS? x "021- 

 •023 mm. _ 



Tlie above description agrees to a certain extent with van 

 Beneden's figure of G aster ostomum triglce. In his figure 

 the yolk-glands are rather far forward, the genital glands 

 are on the left side of the body, the anterior sucker is 

 elongated, and the structure surmounting the sucker is not 

 represented. The absence of this is sufiicient to throw doubt 

 on the identification of my specimens with G. triglce, van Ben., 

 for the structure is usually so prominent in my specimens 

 that it seems impossible that anyone could have missed seeing 

 it. On the other hand, the similarity in internal anatomy 

 and the fact that both come from the same host are suggestive 

 of their identity. Gasterostoinum triglce, van Ben., can hardly 

 be considered a properly characterised species ; all that 

 van Beneden gives is a figure with not a word of description. 

 It seems inadvisable, however, to create a new specific name 

 for my specimens from Trigla gurnardus ; further research 

 will probably throw more light on their identity. 



O aster ostomum gracilescens, Rud. 



A large munber of immature specimens of this species were 

 found in the stomach of a cod. The latter is not regarded as 

 a final host of this species, although it functions as an inter- 

 mediate host for the encysted cercaria?. Adult Gasterostoma 

 liave never been found in it. The specimens under con- 

 sideration had probably come from some Gadoid fish ingested 

 by the cod, avjd it is doubtful if they would have attained 

 maturity in this host. 



