574 RECORD OF CURRENT RESEARCHES RELATING TO 



the seminal duct iuto the ootyp, and this has been observed by Vogt 

 as filled with semen ; in Pohistomum Zeller has reported the presence 

 of a duct connecting one of the testicular tubes with the ootyp ; iu 

 Microcotyle the testicular bodies open directly into the ootyp. As to 

 the appended structures, penis, penial glands, and so on, the variety 

 is extreme. Great difficulties surround the explanation of the arrange- 

 ments that obtain in Diplecianum, which M. Vogt hopes to be able 

 to resolve on another visit to Roscoff. 



This paper is reviewed in part iii. of M. Lacaze-Duthiers' ' Ar- 

 chives ' for 1877, which was only published early this year. 



Organization of Axine and Microcotyle.* — The specimens for 

 Herr Lorenz's examination of these interesting Trematodes were 

 chiefly obtained at the Zoological Station at Trieste. 



Axine helones is a parasite of the fish Belone esox, on the gills 

 of which it lives; first described by Abilgaard in 1794, it has 

 since been observed by various zoologists, among whom are Van 

 Beneden and Hesse, and in the opinion of Herr Lorenz the form 

 described by them, A. orpliii, is identical with Abilgaard's species. 

 From four to eight mm. long, with an acute anterior, and a broad 

 hinder end, it is of a milk-white colour, and almost transparent ; but 

 it is chiefly I'emarkable for its asymmetry ; the right side is the 

 longer and is convex, while the left is faintly concave ; four groups 

 of hooks or chitinous rods surround the anus ; iu the centre there are 

 eight to twelve hooks, and on either side there are from twelve to 

 twenty hook-shaped rods, while at the base of the cirrus there are 

 from sixteen to twenty-four. The external integument is formed by a 

 delicate caticle, between which there is a thin layer of finely granular 

 l^rotoplasmic substance. Of muscular fibres there are two kinds ; 

 one longitudinal, and ending in fine filaments, and the other formed by 

 a tissue of much more delicate fibrillte, which run in three distinct 

 bands. The seizing organs, which are not suckers, though they have 

 their function, occupy the whole of the hinder edge of the body : the 

 nerve-centre is apparently represented by a curved band, which lies 

 in the parenchyma of the body above the cesophagus, and consists of 

 yellowish-coloured fibrous and finely granular substance ; the fine 

 fibres given oif from it are very soon lost in the parenchyma of the 

 body. Anteriorly to the mouth there is a funnel-shaped cavity, with 

 a right and left sucker ; these latter are formed of a thick muscular 

 integument, which is traversed by a number of closely set radial 

 muscular fibres. The oesophagus forms a simple tube as far as the 

 common generative orifice, where it divides iuto the two arms of the 

 enteron, which soon take on a dendritic api>earanco, owing to the 

 presence of short ca3ca. The two arms do not unite at their distal 

 end ; the enteron does not seem to have any special wall, but to be 

 merely a cavity in the parenchyma of the body ; it is, however, jiro- 

 vided with a number of pigment cells, which are filled with small 

 dark-brown granules. The excretory vascular system of Axine is very 

 well devcloj)ed, and has the form of two internally ciliated longitu- 



♦ 'Arbeit. Zool. lust. Univ. Wien.,' iii. (1878) art. ii. 



