428 Dr. Knox's Notice of a Sword-Fish 



the fin, or lophiodermic portion, which not only suffers a manifest 

 interruption, having altogether disappeared for the space of nearly 

 three feet, but has its place occupied by a structure altogether pe- 

 culiar, and differing from what we should have expected, had this 

 part of the back ever been occupied by a series of bones, and an 

 elevated portion of the skin, — in plain language, by a fin having a, 

 proper ichthyological character. To suppose that all this has dis- 

 appeared by the mere effect of age, were altogether unreasonable ; 

 and to imagine it to be caused by an accidental laceration, were an 

 assumption gratuitous, and refuted by bare inspection of the parts. 

 For in place of portions of this dorsal fin, which might reasonably 

 have been expected to have remained in fragments at various inter- 

 vals, if laceration had been the cause of its imperfection, we find 

 ajQ uniform smooth surface, of a whitish colour, and therefore con- 

 trasted with the neighbouring parts of the skin, — of a somewhat dif- 

 ferent texture, being rather softer, — and characterized by^a series of 

 openings, placed at the distance of about 1 or li inch from each 

 other, of an oval shape, large enough to admit of the insertion of a 

 tolerably sized crow-quill. These apertures have a defined edge, 

 and lead to somewhat elongated culs de sac, lined by a mucous 

 membrane, and having no communication with each other ; deeper 

 than these cavities, and unconnected with them, except that they 

 were placed immediately below them, are found the spines, whicn 

 are obviously the skeleton of the dorsal fin, resting on the spinous 

 processes of the vertebrae. No one, I think, conld say that these 

 were mere accidental appearances ; they seem to be rather a cha- 

 racter of this part of the animal. 



I shall send for your next number a sketch of what I have de- 

 scribed, and then naturalists may judge for themselves ; but, in the, 

 meantime, until the fin of the young Xiphias be dissected, and the 

 fact of a continuity of all its parts, osseous as well as dermic, shown 

 to hold in youth, I must consider the opinions which have been ad- 

 vanced on this matter to be mere assertions. 



There is then a species of the Xiphias in which the dorsal fin 

 appears to be interrupted ; and the question consequently is, whe- 

 ther this be a character which it possesses at birth ? if so, is it spe- 

 cific ? Does it come on with age ? an opinion, to say the least of it, 

 extremely improbable ; or is it sexual ? * I cannot allow the opi- 

 nion, that it is a mere accidental laceration, to occupy me for one 

 moment. 



The anal fin was not quite interrupted ; it was merely very low. 

 A slight ridge of skin marks its presence in the middle of the fin, 

 but it contains in this part no osseous spines nor skeleton. Por- 

 tions of it were so far detached from the larger anterior part, that 

 they seemed at first to be entirely separate, and appeared to pro- 

 ject, (though I should not wish this to be considered as certainly 



• Dr. Xeach's specimen and mine were both females. 



