524 Mr. W. Nicoll on some 



specimens occurring there in considerable numbers and of 

 n)uch larger size than those in the intestine. One ex- 

 ceptionally large specimen reached a length of 1'56 mm. and 

 the others all exceeded 1 mtn. It was noticeable that, in 

 passing down the intestine, the specimens tended to increase 

 in size. 



The advisability of making a new species for the Levinsenia 

 from the gulls has been discussed hy Jagerskiold. While 

 inclined at tirst to regard it merely as a variety of L. pygmcea, 

 he later * raised it to the position of a distinct species. 

 Further he makes it the type of a new genus, Spelotrema, 

 including Distomum pygmeeum, macrophnllos, and. claviforme, 

 distinct from the genus Levinsenia, of which D. hrachysomum 

 was tiie type. Looss f, however, does not entirely agree 

 with this, maintaining that as D. hrachysomum was a species 

 inquirenda it could not be employed as a genus type, and 

 that therefore the name Levinsenia ought rightly to remain 

 for the species included under Jagerskiold's Spelotrema^ with 

 Lj. similis as the type. 



That my specimens are identical with those of Jagerskiold 

 there can be little doubt, despite the disparity in size. The 

 relative size of the suckers, which enabled Jagerskiold to 

 differentiate L. similis from I^. pygmcea, is usually a point of 

 diagnostic importance. In this respect my experience agrees 

 with that of Jagerskiold ; although it is certainly a matter 

 of some difficulty to decide in this case, for in many examples 

 the ventral sucker, by reason of con)pression, acquires an 

 elliptical form, the long axis being as often longitudinal as 

 transverse. In a large series of measurements it was found 

 that the ventral sucker was in most cases, if not all, slightly 

 larger than the oral. The inclusion of JDistomum claviforme, 

 Brandes :J:, within the genus Levinsenia is open to question. 

 As Jagerskiold says, it is a species impossible to identif3% 

 Biandes's figure certainly leaves much to be desired and his 

 di scription is by no means full. Jagerskiold^s interpretation § 

 of Brandes^s figure is plausible and seems necessary if Z^. clavi- 

 furme is to take its place alongside the other species in the 

 genus Levinsenia. On this assumption it would bear a very 

 strong resemblance to my specimens of L. similis both in 

 shape and structure, for it has the typical club shape, although 

 of much smaller size (•3-'4 mm.). 



Brandes sees in Distomum claviforme the adult of the 



* Centralbl. Bakt. xxx. p. 982 (1901). 

 t Zool. Jahrbiicher, xvi. p. 705. 

 X Arc-h. f. Niitiujr. liv. j). 247. 

 § CeiUialbl. Baki. xxvii. p. 739. 



