Dr. Johnston on Entozoa. 433 



lar parenchyma than a distinct formation with proper coats. 

 These are the intestinal canals. I cannot trace their rise, nor 

 their continuation to the mouthy but their termination in the 

 anus is evident, previous to which they may be observed to 

 nigh one another. Where we first see them near the head, 

 they are fringed with short obtuse canals or caeca, that extend 

 down about a third of their length, the rest of the intestine 

 being simple and undivided. 



The vascular system is beautifully developed, and distin- 

 guished by the milk-white colour of the vessels. On each 

 side there is a large trunk, which begins in the anterior central 

 or medial organ and runs forward to the mouth; while another 

 of the same size runs backwards to the sucker. From these 

 main trunks numerous lateral branches issue and divide into 

 lesser branchlets, which lose themselves about a line from the 

 margin ; for this is quite clear and unvascular, and is not filled 

 even with the granules of which the whole interior of the 

 worm seems to be composed. 



This is, I fear, a very imperfect description of a very curious 

 animal, but it is the best I have been able to make, and is 

 well illustrated by the beautiful figure which accompanies it. 

 To determine the connexion and nature of the organs seems 

 to me a doubtful and difficult task. The mouth may be pre- 

 sumed to be ascertained and to have a suctorial character, al- 

 though Oth o Fabricius placed it at the opposite extremity in 

 the centre of the caudal discs. The functions of the viscera 

 behind it are conjectural. I have sometimes thought that the 

 two foremost (b) were stomachical, but have been unable to 

 trace any canal of communication between them and the mouth 

 or the intestines ; and it may be that they are rather subser- 

 vient to generation, standing in the place of the male organs. 

 The nature of the intestinal canals is not disputable : their 

 course and termination in the anus prove their office, and they 

 are extremely like the alimentary canal of the Diplozoon, an 

 evidently affined animal, in which Nordmann ascertained the 

 functions of the parts in question. The organ marked (o) is 

 evidently connected with the reproduction of the species. 

 Nordmann calls an exactly analogous organ of the Diplozoon 

 a testicle, and the long thread-like filament he believes to be 

 Ann. Nat. Hist, Vol.1. No. 6. August 1838. 2 f 



