296 M. Krohn on the Anatomy and 



kept in the same vessel, I rarely remarked that they devoured 

 one another, or that they were inclined to do so. 



The ovaries have been already described by MM. Quoy and 

 €raimard. Each ovary is a pouch terminated anteriorly in a caecum, 

 and fixed by a slender ligament to the inferior wall of the cavity 

 of the trunk ; it extends in a straight line from anteriorly back- 

 wards, parallel to the corresponding margin of the inferior mus- 

 cular band, and lastly forms a loop, on rising towards the dorsal 

 surface of the animal. There it opens exteriorly between the 

 upper muscular band and the base of the last fin. I fancied that 

 I perceived in the sides of the ovarian pouch, under a strong 

 magnifier, thin fibres, which, where the germs of ova (stroma) 

 occurred, appeared to form two interlaced layers. The stroma, 

 which may be detected throughout the whole length of each ova- 

 rian pouch, only exists in the half of this organ, in relation with 

 the ligament. 



The length and the vddth of the ovaries, very variable accord- 

 ing to the age of the individuals, are in direct relation, as may 

 easily be conceived, to the number and development of the egg& 

 contained in them. In individuals of two lines and a half in 

 length, only feeble rudiments of them are seen ; the ovules are 

 then extremely small. These ovaries increase more and more in 

 length and breadth up to the adult age, that is to say, up to the 

 moment of coition, at which period they are seen to project 

 above the first pair of fins*. All the eggs, the smallest as well 

 as the largest, exhibit a germinal vesicle ; but no circumscribed 

 germinal spot can be discovered in them. The vesicle appears of 

 a relatively very considerable volume in the youngest ovules ; it 

 increases at first a little in size in proportion as the vitellus di- 

 minishes ; but it remains at length stationary, — relations which 

 exist in all known animals. When we examine very developed 

 ovaries, we find that the youngest ovules are appended to the 

 stroma by a short pedicel, whilst the most advanced ovules, which 

 are surrounded by a very visible chorion, are not provided with 

 this pedicel. 



III. Tail: — Seminal cells. — The cavity of the tail is divided 

 throughout its length by a vertical partition attached to the 

 transversal septum, which limits posteriorly the cavity of the 

 trunk, and is thus divided into two cells perfectly independent of 

 one another. It is in these cells, as we have already stated, that 



• There are however exceptions to this rule : the ovaries are sometimes 

 less developed in the large individuals than in other smaller ones. I re- 

 member in particular an individual the length of which was only three- 

 quarters that of a normal adult, and in which the fecundation nevertheless 

 took place in the interior of the ovaries, which were highly developed. 



