13(5 PHILOSOPHICAL TUANS ACTIONS. [ANXO 1/81. 



Anal Jin united with the caudal, whitish at the base, black on the margin, furnished with simple 

 rays. 



Caudal Jin black, with obtuse tip. 



The scales of the ophidium, which have been figured by Rondeletius, but 

 overlooked by many other writers, have been mentioned by Willoughby, but 

 without any particular description. They are very different from those on the 

 skin of the ophidium imberbe, which are shortly described by Gronovius. Their 

 position, as may be seen in the figure, is irregular. They are dispersed over the 

 whole body. Their form is sometimes round, sometimes nearly oval. They are 

 larger near the head, and in the lower part of the body ; but are hardly to be 

 distinguished near the tail. They adhere to the body by means of a particular 

 transparent skin, which is in general very thin, but somewhat thicker near the 

 neck, and extended loosely over the whole head : this skin is very easily des- 

 troyed, after which the scales falling, the body appears spotted (fig. l, pi. 3.) 

 These scales are of the same sort as those that Leeuwenhoek has described on 

 the eel, like those I have seen on the anarrhichas lupus, the blennius viviparus, 

 and many other fishes, which are commonly thought to be without scales. When 

 you look at them with the naked eye (fig. 1,) they appear as covered with very 

 small grains; but viewed through a microscope (fig. 3,) the middle of them ap- 

 pears more elevated than the margin ; and from the centre to the margin, close 

 by each other, there are many lines or rays, formed by small scales, placed one 

 upon another, like tiles on a roof, the superior being always the nearer to the 

 centre. This sort of scales, which may be called umbonatae, are fastened to the 

 body by very small vessels inserted in their middle ; they are to be seen on the 

 body only, not on the head nor the fins. 



I shall now proceed to the anatomy of this fish, which certainly comprehends 

 some very remarkable circumstances, which, I believe, have not yet been ob- 

 served in any other species. When we have drawn off" the skin, there appears 

 a thin membrane of a silver colour, which covers the muscles. The muscles 

 being removed, we find the peritoneum, which lines the abdominal cavity, and 

 is adherent to the swimming bladder by some elongations. It is of a silver hue, 

 with some very small black points. The ventricle is not to be distinguished from 

 the intestines by any other mark but by its size: its form is oblong; it is ex- 

 tended almost to the anus, whence the intestinal duct has a retrograde course, 

 and then descends again, having a little dilatation near the anus. On the verte- 

 bras next the anus, on the outside of the peritoneum, is a kind of cavity of an 

 oblong form, containing a reddish viscus, which I take to be the kidney. 



The first vertebra from the head has nothing very remarkable in its structure. 

 The 2c\ has on each side an elongated and sharp apophysis, to the apex of which 

 is annexed a small ligament. The 3d is very flat, and has on each side a kind of 



