349 
XVIII. Further Observations on Entozoa, with Experiments. By T. Spencer Cobbold 
M.D., F.L.S.* 
Read December 20th, 1860. 
ALTHOUGH, since my last communication, I have had fewer opportunities of examining 
Entozoa, I think it will be admitted that the new or otherwise important forms which 
have come under my notice, are of sufficient interest to be placed on record, in continu- 
ation of the series of papers previously submitted to the Society. 
In the present instance, the number of different animals specially examined with refer- 
ence to the presence or absence of internal parasites, amounts in all to forty-three, in- 
cluding seven fish, two reptiles, seventeen birds and nineteen mammals. Of these onh 
three fish, one reptile, seven birds and the same number of mammals, were found infested. 
In so far as these numbers refer to species formerly living in the Zoological Society's 
menagerie, the proportion is small, and tends to confirm both the statement and explana- 
tion which I have before hazarded in respect of the comparative freedom from internal 
trematode parasites, found to obtain in foreign animals subjected to a condition of 
captivity. 
1. DlSTOMA 
of life 
Distoma conjunctum, Cobbold, Linn. Soc. Proceed, vol. v., Zool. Div. p. 8. 
Bemarks.-An already briefly indicated in my synopsis of the Distomitte, published in 
the Society's Proceedings (Ice. ciL), this species of fluke infests the liver of the American 
Red Fox (CM.il*>* The animal in question died at the Zoological Society s Gardens, 
Regent's Park, in December, 1858, and was dissected on the 2 1th of that month the carcase 
being still quite fresh. The biliary ducts were found thickened and enlarged m several 
places, forming here and there small cysts of variable size. In these cavit tes-partly occu- 
pied by purulent matter-the distomes were lodged ; and when placed in water they showed 
- - 1 _ Their extreme transparency at once displayed, under the microscope, the rela- 
tive position and degree of development of the various organs, as shown by the accompany- 
ing figure (fig. 1, Plate XXXIII.), in which I may particularly remark the great breadth of 
the digestive cteca, the well-defined excretory canals passing transversely inwards from the 
botry oidal albumen-forming glands (Dotterstock) , and also the large yelk-forn^ng organ 
or ovary (Eikeimstock), placed in the centre of the body, immediately below the uter ne 
folds. A still more noticeable feature, however, is seen in the unusual length and bread h 
of the contractile vesicle belonging to the excretory system. It occupies M^*™ 
of the longitudinal diameter of the body, and bifurcates at the summit the course oi each 
division being traceable almost as far forward as the bulb of the (esophagus^ below 
suddenly constricted, and terminates, as usual, by a small central aperti 
The sac itself 
An abstract of this paper has been published in the Society's Proceedings, Zool. Div. vol. v. p. 235. 
