248 



Mr. W. Nicoll on the 



Spelotrema feriatum, sp. n. 



Tocotrema jejunum, sp. n. 

 Monostomum petasatum, Deslon(jch. 

 Numenms arquafa, Lath. Curlew. 

 Y Ecliinostomum secundum, Nicoll. 



Vanellus vanellus (Liuu.). Lapwing. 

 Spelotrema feriatum, sp. n. (juven.). 



ALyialitis hiaticula (Linn.). Ring-Plover. 

 Maritrema gratiosiim, sp. n. 



Spelotrema feriatum, sp. n. 



Spelotrema claviforme [Bnh.), 



Ild'tnatopiis ostralegvs, Liun. Oyster-catclier. 

 Maritrema gratiosum, sp. n. (juven.). 

 Spelotrema feriatum, sp. n. (juven.). 

 Psilostomum brevicoUe (CrepL). 



Intestine, c?eca, and 



rectum. 

 Intestine. 

 Cajca. 



Intestine, cteca, and 

 rectum. 



Intestine, coeca, and 

 rectum. 



Intestine and duo- 

 denum. 



Eectura, caeca, and in- 

 testine. 



Intestine, rectum, and 

 caeca. 



Intestine. 

 Intestine, 

 Intestine and caeca. 



Genus Spelotrema, Jligerskiold. 



Spelotrema excellens, sp, n. 



= .S)j, simile, Jiigersk., Nicoll, Ann. & Mag, Nat. Hist. (7) xvii. 

 pp. 522-524. 



From other members of the genus this species is dis- 

 tinguished by its comparatively large size. In a former 

 note I commented on the great difference in size between 

 my specimens and those of Sp. simile, obtained by Jager- 

 skiold from the same host. Beyond this I could find no 

 difference of sufficient importance to warrant specific dis- 

 tinction, and the occurrence of the two forms in the same 

 host was a reason for regarding them, if not identical, at 

 least merely as two varieties of the same species. It not 

 uncommonly happens, however, that two or even more 

 species of the same genus inhabit the same host. 



Jagerskiold found a similar difficulty in distinguishing 

 between his form and Sp. pygmaum (Levins.), The two 

 forms are nearly of the same size and practically the only 

 differences between them consist in the reversed ratio of the 

 suckers, which, however, are very nearly equal, and in 

 the size of the '^ genital body." It is to these features that 

 I, also, am obliged to turn, in order to obtain marks to 

 differentiate my specimens. 



Since first obtaining this form I have met with it several 

 times again, always in Larus argentatus, never in any other 

 host. Renewed observations and measurements confirmed 



