SVVOKDI'ISH. 151 



fin, although shorter, in other particuLars resembk^s the dorsal. 

 The pectoral fin is situated low down, and its upper rays are 

 long and ])ointcd; the tail deeply forked. The dorsal fin, 

 when complete, has, according to Risso, forty-two rays; anal 

 eighteen; caudal twenty-six; pectoral seventeen, which arc firm 

 and bent like a scythe. The colour is dark, almost black on 

 the back and tail, lighter on the sides, and white below; but 

 in the IMediterranean the back is described as being of a steel 

 blue. Pectoral fin yellow. 



Doctor Caius, (Keys.) Avho lived in the middle of the six- 

 teenth century, and wrote a well-knoMm "Natural History of 

 British Dogs," was the earliest of modern writers who notices 

 this species, which he did in a communication to the naturalist 

 Gesner, where he particularly describes the sword-like snout, 

 from a dried specimen. He says that the upper part of this 

 beak is altogether hard and bony, and, as Aristotle says, equal 

 in length to the rest of the body. It is formed of two bones, 

 which are so closely joined along their course from the point, 

 as to appear like a single bone. Near the head they gradually 

 separate, so that the upper one rises in a broader form, to 

 constitute the skull, and the lower becomes the bone of the 

 palate, — the brain and eye being thus situated between them. 

 Along the middle of the beak or sword there runs a depression, 

 and a shallower one on each side of it, with a suture on the 

 lower side; nothing of which can be discovered in the recent 

 specimen. 



It has been observed that in the development of fishes from 

 the egg, the ventral fins are the last of all the organs to make 

 their appearance. Their absence, therefore, in many genera 

 constituting the order of apodal fishes in the system of Linnaeus, 

 is to be understood as an arrest of development, and of which 

 the genus Xiphias approaches the most nearly to the orders 

 above it, by its close affinity to other Swordfishes which have 

 these fins in perfection. 



