52 NATURAL HISTORY. 



latter movement is effected solely by the aid of the pectoral fins, the tail being collapsed and not used. 

 From the body being buoyed up with so much air the branchial openings were out of the water ; but 

 a stream drawn in by the mouth constantly flowed through them. The fish having remained in this 

 distended state for a short time, generally expelled the air and water with considerable force from the 

 branchial apertures and mouth. It could emit, at will, a certain portion of the water ; and it appears, 

 therefore, probable that this fluid is taken in partly for the sake of regulating its specific gravity. This 

 Diodon possessed several means of defence. It could give a severe bite, and could eject water 

 from its mouth to some distance; at the same time it made a curious noise by the movement of its 

 jaws. By the inflation of its body the papillae, with which its skin is covered, became erect arid 

 pointed. But the most curious circumstance was that it emitted from the skin of its belly, when 

 handled, a most beautiful carmine -red and fibrous secretion, which stained ivory and paper in so 

 permanent a manner, that the tint is retained in all its brightness to the present day." 



There are five genera closely allied to Diodon. Chilomycterus possesses a species (Chilomycterus 

 geometricus) which, though widely distributed in the tropical parts of the Atlantic, is found in Lake 

 Champlain and several inland watei-s of the United States; but most of the species of this genus 

 belong to the Indian Ocean and adjacent seas. In the genus Trichodiodon, which frequents the 

 North Atlantic, the spines on the body are reduced to delicate hairs : an example in the Paris 

 Museum has a length of thirty inches. In Trichocyclus the spines become elongated like bristles, 

 and the dorsal and anal fins are entirely absent. 



The third division of the Gy mnodontes contains only the Sun-fish ; and this group, represented by 

 a single genus, is named,- from its typical species, Molina. The Sun-fishes belong to the genus Ortha- 

 goriscus. The body is short and compressed, and covered with a rough or tesselated skin, which is 

 not capable of being expanded as among the Diodonts. The air-bladder is absent, there is no pelvic 

 bone, the ventral fins are wanting, and the vertical fins are all placed together at the hinder part of the 

 body, and often are so arranged that the dorsal and anal fins seem but lateral lobes of the caudal fin. 



The Common Sun-fish (Orthagoriscus mola) inhabits the open sea, and has been met with in many 

 parts of the world in temperate and tropical waters. It is not uncommon in Australia, where it is 

 valued for the quantity of oil which it yields. Every year a few specimens are taken during the 

 warmer months on some part of the British coast, even as far north as the Orkneys. It is usually 

 captured floating on the surface, when it appears languid and almost asleep, with its head projecting 

 out of the water, but it is sometimes foxind lying on its side, and is then probably sick, though the 

 fishermen regard this as an indication of continued fine weather. In this state it is not alarmed by 

 the approach of the fisherman, though, when the opportunity offers, it makes its escape over the 

 surface faster than a rowing-boat can follow. When laid hold of these fishes utter sounds which 

 some fishermen have compared to the loud grunting of a hog. When anything approaches the eye- 

 ball, the ball is drawn into the socket, and a membrane rises up from the base and covers it. The 

 Sun-fishes appear to retain their vitality for some time out of water, for a specimen kept in a boat for 

 half an hour, on being thrown back into the sea is said by the fishermen to have darted away like an 

 arrow. CWch mentions, on the authority of a friend, that when cooked for the table it is good 

 eating, and has much the flavour of the Common Crab, but in England no use is made of it. Its 

 food is variable, and the stomach has been known to contain seaweed, corallines, and barnacles, 

 though nothing but mucus is usually found thei*e. Sometimes the species reaches an enormous size. 

 The largest British specimen known is seven feet nine inches long, and eight feet six inches deep 

 across the fins, but the proportions change with age, and in very young examples the vertical diameter 

 exceeds the length, while in older examples the depth is somewhat more than half the length. With 

 age a hump is developed above the mouth, and on this there is a bony tubercle, while in very young 

 specimens this position is marked with a spine. Young examples, too, have spines scattered over the 

 body, and in the region of the throat some of these are converted into osseous tubercles, and remain 

 throughout life. The teeth undergo a remarkable modification. In the young state there are 

 supplementary teeth within the cutting jaws, and these teeth are generally met with till the fish 

 attains a length of eighteen inches, but when the animal has become twice as long they have entirely 

 disappeared. The head is thicker than the body, and has an elevated ridge above the eye. The small 

 mouth is placed below the blunt nose, and is capable of but little movement. Each jaw has the 



