Trematude Parasites "f British Birds. 257 



possess no sectional preparations tliis evidence is not con- 

 clusive. The ventral sucker in Ticotrcma concavum a|)pears 

 to be in a more degenerate condition than in T. linfjvu. 

 Moreover, the voluminous vcsicula seniinalis of the hitter is 

 >ery much reduced, in the former. A less important differ- 

 ence is the symmetrical arrangement of the testes in Toco- 

 trema concavum in contrast to the oblique arrangement in 

 T. Ivujua. 



The occurrence here of a new species agreeing very closely 

 with 7< cotrema lingua accentuates the difference between 

 the latter and Distomum concavum. Moreover, considering 

 the large number of hosts from which Distomum concavum 

 has been recorded, it is quite possible that two or more 

 closely similar species may have been confused. The form 

 which I have obtained from Phalacrocorax graculus is almost 

 identical with Distomum concavum, but it difiers from 

 Muhling^s description in one or two important features 

 which may cause it to be regarded as distinct. Distomum 

 Mueliliugi shows considerable resemblance to Tocotrtma lingua, 

 and if it should prove to have a genital sucker, a> opposed to 

 INliihling's description, it would be classed in tlie same groun. 

 For these reasons lam inclined to regard Distomum concavum 

 as the type of a genus distinct from, but closely related to, 

 I'ocotrema. To this genus Liihe's name Cryptocotyle, 

 liitheito regarded as a synonym of Tocotrema, miglit con- 

 veniently be applied. Liihe took Distomum concavum as 

 type, while the genus Tocotrtma is fouudeil on Distomum 

 lingua as type. 



1 ocotrema jejunum, sp. n. 



This species occurred fairly frequently in 7'otanus calidris. 

 It is of somewhat smaller size than T. lingua, the len"-tii 

 varying from '87-l'77 mm., but the normal lengtii is 

 probably not beyond I'S mm. It displays, however, an 

 extraordinary amount of extensibility. Almost every ex- 

 ample was well extended, and in a large number the extension 

 was so great that thev had almost the appearance of threads 

 the body being often bent and twisted in a grotesque fashion. 

 As might be expected, the uuiximum breadth occurring in 

 the posterior part of the body is not at all constant, varvin*'- 

 from I to 1 of the body-length. The normal figure is 

 probaljly about }, being found in examples of l-() uim. to 

 i-2 mm. long, the shape is not like that cf T. lingua, the 

 anterior part of the body being more tapering and the 

 posterior j)art more rounded. In a normal specimen (1-0- 

 12 mm.) the oral sucker measures -Old mm. The ventral 



