Tre7natode Parasites of British Birds. 251 



anterior end, is not convoluted to the same extent as in 

 Sp. simile : its course is, in fact, almost direct, albeit sliglitly 

 sinuate, towards the genital body. This difference may 

 be of specific importance. The testes are shaped and 

 situated exactly as in Sp. pi/z/i/Keum'^, not as represented 

 in my figure. The outline is oval with the long axis directly 

 transverse. They are usually enveloped to a large extent by 

 the uterus. The right testis is just behind tlie ovary, while 

 on the left the anterior border of the testis is almost con- 

 tiguous with the genital sucker. They measure •14--16x 

 •OH-'ll mm. The ovary is on the right of the ventral 

 sucker and is contiguous with it, the right intestinal diver- 

 ticulum, and sometimes the vesicula seminalis. Its shape is 

 somewhat variable, being pear-shaped, oval, or more irregular, 

 but in all cases the long axis is directed obliquely down- 

 wards to the middle line of the body; size -lO-'llx-Or- 

 '08 mm. The uterus starts from tlie posterior end of the 

 ovary, and passing down the middle of the body forms a 

 series of convolutions first on the right side and then on the 

 left. The convolutions are so voluminous that no regular 

 arrangement is apparent. The uterus fills practically the 

 whole of the posterior part of the body not occupied by 

 the testes and yolk-glands. Its anterior limit is the level of 

 the anterior border of the ventral sucker. The ova are very 

 numerous, colourless on the right, bright yellow on the left. 

 This would appear to be a further point of distinction 

 between this species and Sp. simile, for, according to Odhner, 

 the ova in the latter are all colourless, a feature serving to 

 distinguish it from Sp. pygmcei/m, in which the condition is 

 the same as in Sp. e.vcellins. The ova measure -023-025 X 

 •010--013 mm. The yolk-glands are difficult to make out, 

 being obscured by the ova. They lie behind and ventral to 

 the testes, which they overlap to some extent. They appear 

 to consist of a number of lobes on each side, but the arrange- 

 ment and the exact number of the lobes I am unable to deter- 

 mine with certainty. Comparison with Sp. jji/ffinaian and 

 the next species to be described would point to their number 

 being about eight on each side. The yolk-ducts are usually 

 visible, uniting just behind the ventral sucker, the common 

 duct passing towards the ovary. 



Spetotrema feriatum, sp. n. 



This species occurred very numerously in Pelidna alpina, 

 Totanus calldris, and JEgialitis hiaticula, less frequently and 



• Odhner's figure, loc. cit. 



17* 



