496 ALBERT W. BROWN. 



preying on Aratnocoetcs is obtainable. Most Holostomids 

 have birds as final hosts, but in the places from which my 

 Aramocoetes were brought there are not many birds to prey 

 on them. 



Yarrel, in his ' British Fishes/ states that eels prey on 

 Ammocoetes. I obtained some large eels, starved them for a 

 time, and then tried to feed them with Ammocoetes, but 

 neither alive nor dead would they touch them. 



The most puzzling question of all to decide is how the 

 parasites get into the brain. Possibly they reach it by means 

 of the blood-vessels, but this seems rather improbable in 

 spite of the apparent ease with which Ammocoetes can stand 

 injury to the brain. It seems more probable that they get in 

 before communication between the brain cavities and the 

 external world is interrupted. There seems, however, no 

 possibility of them getting out again without killing the 

 animal, and their ultimate fate is at present a mystery. Do 

 they kill off the forms they infest after a certain time ? To 

 determine this it would be necessary to keep a large stock of 

 Ammocoetes and examine carefully all who died off. 



It is almost incredible that any vertebrate could live on, 

 apparently without discomfort, whilst its brain is packed with 

 hundreds of flukes. It is true they do not appear to damage 

 the brain substance, but they must consume a great deal of 

 nourishment intended for the brain itself, and their excretory 

 products must surely interfere in some way with the proper 

 brain functions. 



I have thought it well to publish these brief notes on this 

 interesting form, although my attempts to solve its life-history 

 have thus far proved ineffectual. The existence of so highly 

 organised a form as a Trematode in the brain cavity of a 

 vertebrate is a unique phenomenon in many ways, and this 

 must commend it to the interest of all naturalists. For one 

 thing it shows that even the brain is not exempt from the 

 attacks of Trematodes. 



Gulliver's statement of the occurrence of this form did not 

 attract the attention it deserved, and he only gave an outline 



