685 



of the intestine and Brandesia buried in. a Lieberkiihn's crypt 

 which is of course open to the lumen of the intestine (Miihling, 

 Zool. Anz. Nr. 549. 1898. p. 23). 



Disregarding the position of the genital opening L. m^cammi most 

 closely resembles P. medians. In shape it is much shorter in pro- 

 portion to its breadth, surpassing even Pi-osotocus confusus in that 

 respect, but it is broadest behind instead of in front and emarginate 

 at the posterior end from which the large excretory vessels widely 

 diverge. The oesophagus is very short and the coeca broadly spread- 

 ing, while in P. medians there is a long oesophagus and the coeca are 

 larger and less divergent. The ovary is irregular (lobedj instead of 

 rounded (compact) and is situated just inwards from the right 

 coecum instead of outwards. The uterus folds back and forward in 

 passing across the body behind the coeca instead of folding right 

 and left while forming a long loop back and forwards on each side 

 of the post-acetabular half of the body. The testes are similar, 

 irregular bodies placed obliquely right and left of the acetabulum, 

 at the ends of the coeca, but the penis-apparatus is smaller in 

 L. arcanum than in P. medians and opens on the surface instead of 

 at the margin. The vittellaria extend from the pharynx to the ends 

 of the coeca all across the body ventral to the intestinal system 

 instead^of being on each side of the oesophagus as two dorsally 

 situated distinct groups of follicles. The eggs in preserved speci- 

 mens of L. arcanum vary about 0,022 X 0,014 (Nickerson says 

 about 23 X 13 (.i) while in P. medians they are 0,03 X 0,016. 



Morphologically there is considerable difference between Loxogenes 

 arcanum and Brandesia turgida. The only characters in which they 

 particularly approach each other are the size of the worms and the 

 size and position of their suckers. My largest specimen measures 

 1,9 X 1,28 (not 3 to 4 as given by Pratt, which is the length of the 

 thick cysts), Nicker s on' s 2,5, which is also the greatest length given 

 for Brandesia. The ventral sucker I find by measurement to be 

 rather larger than the oral, although it may look smaller, and is 

 situated a little behind the centre of the animal. In Brandesia the 

 oral is the larger and is placed rather farther back. The peculiar 

 form given by Brandes (Arch. f. Naturg. 1888 Taf. 17 fig. 2) was, I 

 fancy, a phase in a single instance; the more normal form is doubt- 

 less given by Looss (Zool. Jahrb. XII. 1899. p. 776). Our specimens 

 differ from the European in being broadest behind, indented at the 

 posterior end , and not particularly thick. I take it that the asym- 

 metry of the intestine inNickerson's drawing is a mistake; the inte- 

 stine is essentially the same in both. In L. arcanum the testes are 



