133 



of Filaria in the aldomen of these fishes ; the Filar'ue beiiig those 

 which of all the species of vvornis occuning in serous cavities most 

 closely resemble the Eel in form. Mr. Yarrell was inclined to doubt 

 that Eels are viviparous from several circunistances. The species 

 are known to be most prolific: viviparous fishes, on the contrary, 

 produce but few young at a time, and these are of considerable size 

 when first excluded. In illustration of this latter fact, British spe- 

 cimens of the viviparous Bleriny (Zoarces viviparus, Cuv.,) and of its 

 young as expelled from the parent fish by pressure, vvere exhibited. 

 In sorae Eels examined in September the ova in countless thousands 

 were distinctly apparent under a lens of very moderate povver, 

 although these ova would not be matured till January : the sexual 

 organ, moreover, of an Eel taken in February exhibited the ap- 

 pearances common to that part in female fishes that had recently 

 deposited their ova. Mr. Yarrell stated that comparative exami- 

 nations made at this time of the year upon the two most common 

 species of Eels of our rivers and lakęs, shovved the sexual organs of 

 the sharp-nosed sort (Anguilla acutirostris) to be in a much more 

 forvvard statė than those of the broad-nosed Eels (Anguilla lati- 

 rostris), Skeletons of both species vvere exhibited, shovving the 

 most obvious diffėrences in the size and character of the bones of 

 the head and vertebrcB ; those of the hroad-nosed Eel being nearly as 

 large again as the šame parts of the other species in examples of 

 the šame length. 



By some authorities both Eels and Lampreys have been stated to 

 be hermaphrodites. 



Mr. Yarrell exhibited preparations of the two sexes distinct both 

 in the Lamprey and Lampern, at the time they were about to de- 

 posit their ova and milt ; and gavę the following account of his in- 

 vestigation of this subject. 



" The common river Lampern [Petromyzonjliiviatilis, L.) was ob- 

 tained and examined every week from March to the middle of May. 

 Up to the 19th of April more females than malęs were taken ; but 

 after this period, the females being nearly ready to deposit their 

 roe, the malęs were most numerous, in the proportion of two to one. 

 All the females taken about the 26th of April vvere in a statė to de- 

 posit their roe ; and the milt of the malęs, novv become fluid, passed 

 in a stream from the sheath behind the anai aperture on making 

 slight pressure upon the abdomen. By the lOth of May nearly the 

 whole of those examined had deposited their spavvn. The malęs 

 vvere entirely void of any appearance of milt, and the females at this 

 time might be mistaken for malęs that had not spavvned. The gela- 

 tinous matrix of the ova appeared svvollen and of large size ; and 

 olose examination shovved the ruptured raembrane and extravasated 

 blood produced by the separation of the ova, vvith here and there 

 an occasional ovum still adhering. The kidneys (vvhich have been 

 mistaken for the malė sexual organs) vvere not observed to undergo 

 any alteration either in size or appearance during a long series of 

 examinations. The malęs could be distinguished from the females 

 externally by their larger respiralory apparatus and lips. 



