new and h'tlle-known Trematodes. 5 1 5 



Httrelda f/lacialin. 



Monostomuni attenuatum, Rud. 



Colymbus septenlrionalia. 

 Distomum sp. 



Oagferosteus aculeatits. 



Psilostoimim redactuin, sp. n. 



The following contaitied no TrematoJe parasites : — 



Lams marinu-t (one specimen). 

 Tot anus calidris „ 

 Corvus corni.v ,, 



rV/<7 troile „ 



(Edemia 7iigra (two specimens). 

 Phasianus colchictta (two specimens). 

 Blennius pholis (one specimen). 



Echinostomum secundum, sp. n. (PI. XII. figs. 1-3.) 



In the intestine of a black-headed gull {Larus ridibundus) 

 three specimens were found. The smallest was 0"4 mm. 

 long, the largest 7*3 mm. The body is long and narrow, 

 flattened dorso-ventrally. The breadth varies considerably in 

 different parts of the body. Across the head in the largest 

 specimen it is "33 mm., at the neck (constriction just behind 

 head) '27 mm., at the ventral sucker '52 mm., and at the 

 widest part of the body (on a level with the anterior testis) 

 •70 mm., from which it tapers gradually to the extremity. 



The oral sucker is terminal, but set at an angle of i5° with 

 the longitudinal axis of the body. Its diameter is Tl mm. 

 The ventral sucker, situated at a distance of "7 mm. from the 

 anterior end, measures '33 ram. in diameter. Both suckers 

 are globular and have a circular aperture. 



The cuticle is thrown into transverse folds, which give the 

 surface a rugose appearance. These folds increase in size 

 from the anterior end ; posteriorly they broaden out and 

 become indistinct. The summit of each fold is studded with 

 numerous little spines, which also increase in size in passing 

 backwards. They are almost entirely absent from the poste- 

 rior third of the body. Around the oral sucker appears the 

 well-defined row of cephalic spines (PI. XII. figs, 2, 3, Sp.) 

 distinctive of the genus. The spines are twenty-nine in 

 number and are set on a sort of ridge, which encircles the 

 anterior end except in the mid-ventral line, and forms the 

 " head." With the exception of two at each end they are 

 arranged in a single uninterrupted row. The exceptions are 



35* 



