The Encystment of Bucephalus Haimeanus. 211 



Tlie Bucephalus of Haime is to be found both .it Etaples and 

 in the neighbourhood of Boulogne-sur-Mer. Guided by certain 

 theoretic views, the result of researches followed out upon the para- 

 sitic Crustacea, I have been more fortunate than jnj two skilful 

 predecessors, for I have proved the encystment of this Bucephalus. 



It is upon the garfish (Belone vulgaris) that I have made 

 this observation. This fish (at Boulogne the onaquereau cVete, at 

 Abbeville the hecasslne de mer) occurs commonly in the market of 

 Boulogne during the months of May, June, and the beginning of 

 July. The viscera of this fish, especially the liver, the genital 

 glands, and the peritoneum are frequently filled with minute cysts 

 having the form of cylinders, terminated at one of their extremities 

 by a bulb hghtly drawn to a point, like a thermometer in construc- 

 tion. By opening cautiously a certain number of these cysts, one 

 finds in some one of them the Bucephalus as yet untransformed. 



My anatomical researches, interrupted in July, were not pushed 

 so far as I should desire. However, I should say, in accordance 

 with Claparede, that it is impossible to arrive at the opinion of 

 M. Lacaze-Duthiers, when he says, in speaking of Bucephalus, 

 " One observes in it a general cavity, that may be considered a 

 digestive cavity." The position of the openings and their phy- 

 siological purposes appear to me to be worthy of being studied 

 anew. 



What becomes of the encysted Bucephalus ? Does it arrive at 

 maturity in the body of the garfish, or does it undergo another 

 migration ? In this latter case, which is the more probable, is this 

 migration active or purely passive ? This it is which remains for 

 discovery. Cla23arede has many times found the Cercaria Haimeana 

 fixed upon the Sarsia and the Oceania. On one occasion the 

 cercaria had lost its two long appendages, but it still wanted the repro- 

 ductive organs. Claparede concludes that this fact was accidental, 

 and that the medusae were but momentary hosts of the Bucephalus. 

 I myself have met an adult Trematode in the coelenteric cavity of 

 Cydippe pileus, which in spring is sometimes cast up in abundance 

 on the shore of Wimereux : but I have no serious reason for sup- 

 posing a genetic relation between this Trematode and Bucephalus 

 HaimeavMs. 



According to Siebold, Bucephalus polymorphus is transformed 

 into Gasterostomum fimhriatwn in the digestive tube of Perca 

 fiuviatilis and P. lucioperca. We also find it encysted in the Cypri- 

 nidae. It seems, then, very probable to suppose that Bucephalus 

 Haimeanus, encysted in Belone vidgaris, is metamorphosed into a 

 species of the genus Gasterostomum in the intestine of some large 

 fish which the garfish is the prey of. In fact, Lacepede assures us 

 that when the garfish quits the deep waters to go to spawn near the 

 shore it often becomes the prey of sharks and large species of 



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