ON THE GENERAL MORPHOLOGY OF THE MYXINOID FISHES. 319 



artery (coe.a.), the latter especially being closely attached to the duct, and somewhat 

 difficult to separate out. All three respectively enter and emerge for the liver at the 

 same place. The branch of the coeliac artery, dividing into the cystic and hepatic 

 arteries, closely accompanies the bile duct — in this case anteriorly. The main stem of 

 the artery courses along the intestine, and may pass over or under the root of the bile 

 duct. In another, and well-injected, specimen the coeliac artery behaved as follows : 

 it arose as a pcm-ed artery, which, after giving oif on each side various branches, e.g., 

 to the pronephros, fused ventrally so as to form a complete ring around the gut in 

 front of the bile duct. From this ring another and smaller circle was given off below 

 the gut which surrounded the bile duct. From the latter arose the branches to the 

 "pancreatic" follicles, the bile duct and gall bladder, and the anterior lobe of the liver. 

 Posteriorly the lesser ring gave off a large branch to the mid-ventral surface of the gut, 

 and the branch to the posterior lobe of the liver. 



In a Bdellostoma cirrhata, Sch., dissected by Dr Dakin, the anatomy of the gall 

 bladder and cystic ducts was found to be essentially the same as in Myxine. 



J. Muller's figure of the gall bladder and ducts may conceivably represent one of 

 the variations which are so common in Myxine, but it is certainly quite inaccurate as a 

 representation of the normal condition. He figures the two hepatic ducts opening into 

 the base of the bile duct. His very brief reference to this region in the text takes no 

 account of the openings of the ducts. The fact that the hepatic ducts may open direct 

 into the gall bladder is, of course, an unusual but not a unique phenomenon. It was, 

 1 believe, first described in the ox by Verheyen in 1710, and occurs as a rare variation 

 even in man. I am not aware, however, of any case so clear and interesting as that 

 of Myxine. 



WiEDERSHEiM, in the first edition of his Lehrhuch (Th. ii, p. 590), publishes an 

 original figure of the biliary apparatus of the Myxinoids, which agrees practically with 

 Muller's figure, and to which therefore the comment above also applies. His remarks 

 are, however, more definite. He says: "Aus jedem Leberlappen tritt ein Ductus 

 hepaticus hervor und diese confluiren zu einem Ductus choledochus, in dessen Riick- 

 wartsverlangerung die Vesica fellea (resp. der Ductus cystieus) gelegen ist." 



Even Maas, in his work on the " pancreas" of the Myxinoids, agrees practically with 

 MuLLER and Wiedersheim. In Myxine he says (p. 3) : " Die Beziehungen der drei 

 Gauge sind so innige, dass zwischen vorderem Lebergang und der Austrittsstelle des 

 Gallenganges nur ein verschwindendes Stlick Gallenblasenwandung liegt, und dass fiir 

 den hinteren Lebergang der Gallengang einfach die Fortsetzung bildet." In Bdellostoma 

 he is more definite (p. 571): "Dieser letztere [bile duct] setzt sich, durch ein en sehr 

 kurzen Ductus cystieus mit der Gallenblase in Communication stehend, aus der 

 Verbindung von rechtem und linkem Lebergang zusammen und miindet wie bei 

 Myxine genau ventral median in den Darm ein." I have repeated my dissections of the 

 biliary apparatus of Myxine a number of times, and find on the whole a remarkable 

 agreement with the conditions already described. The only variation of importance was 



