234 



ICHTHYOLOGY. 



Classifica- the victory over the horses and mules ; these were seen in 

 tion— JIa- every direction, stunned by the frequency and tbrce of the 

 lacopten. g],(,(,i,j.^ (q disappear under water. Some liorses, however, 

 ^"V"""^ rose again, and, in spite of the active vigilance of the In- 

 dians, gained the sliore, exhausted with fatigue ; and their 

 limbs being benumbed by the electric explosions, they 

 stretched themselves out upon the ground." " I remember 

 the superb picture of a horse entering a cavern, and terri- 

 fied at the sight of a lion. The expression of terror is not 

 there stronger than what we ivitnessed in this unequal con- 

 flict. In less than five minutes two horses were already 

 drowned. The Eel, more than five feet long, glides under 

 the belly of the horse or n u'e ; it then makes a discharge 

 from the whole extent of its electric organs, which at once 

 attacks the heart, the viscera, and especially the gastric 

 plexus of nerves." " After this commencement, I was 

 afraid that the sport might end very tragically. But the 

 Indians assured us that the fishing would soon be finished, 

 and that nothing is to be dreaded but the first assault of the 

 Gymnotus. In fact, whether the galvanic electricity is ac- 

 cumulated in repose, or the electric organ ceases to perform 

 its functions when fatigued by too long-continued use, the 

 Eels, after a time, resemble discharged batteries. Their 

 muscular motion is still equally active, but they no longer 

 have the power of giving energetic shocks. When the 

 combat had lasted a quarter of an hour, the mules and 

 horses appeared less affrighted ; they no longer bristled up 

 the mane, and the eye was less expressive of suffering and 

 of terror. They no longer were seen to fall backwards ; and 

 the Gymnotes, swimming with the body half out of the 

 water, and now flying from the horses instead of attacking 

 them, began themselves in their turn to approach the shore." 

 The electric Gymnote is by no means fierce or voracious; 

 but its electric organs are the instrimients by which it pro- 

 cures its prey, and defends itself against alligators and other 

 enemies. It has been se\eral times brought alive to Europe, 

 and some experiments have been made on its electricity, 

 which is conducted and insulated by the same substances 

 as common galvanism. So common is the Gymnotus in 

 some parts of South America, that, in the neighbourhood 

 of Uritucu, a route at one time much frequented has been 

 entirely abandoned, in consequence of the necessity of ford- 

 ing a stream, in which many mules were killed every year 

 by these subaqueous electric shocks. 



The genus Sternarrhus of Schneider was so denominated 

 from the anus being near the sternum. The Gymnarchus 

 niloticus is named in Arabic "Del e far." 



Sub-Order II.— APODES ARTHROPTERYGII. 



Dr Kaup, for the reason stated in the text, has separated Gym~ 

 notns from the Serpentiform Apodals, and associated it with Rur- 

 narckus and its allies, forming a group placed by him next the 

 Malacopteri abdominales, but the want of ventrals necessitates 

 its separation as a sub-order. 



Family I.— GYMNOTID^. 



Eel-like, the back round, and without fins; pectorals; largely- 

 developed anal fin, extending either to the point of the tail, or leav- 

 inL^ the extremity free; with or without teeth on the pre-maxil- 

 laries, mandible, and palatines ; no teeth on the vomer; scapular 

 arch attached to the head ; from the fifth vertebra onwards distinct 

 ribs encompass the belly, and in many species are perceptible 

 through the skin; stomach caecal ; pancreatic casca ; ovisacs pouch- 

 shaped, and their outlets different from those of the Eels; vent 

 and the genital papilla behind it on the coracoid bone, or still 

 farther forward towards the middle of the m-indible. 



The small fore-bladder under the second, third, and fourth ver- 

 tebras is pyriform or heart-shaped, and is double; the outer one 

 being thick, white, and easily torn ; the inner one transparent, 

 filled with a gelatinous fluid, and swimming loose in the outer one. 

 This bladder is attached to the acoustic bones of the skull, and is 

 connected by a fine chord with the simple posterior or ordinary 

 Bwira-bladder, which chord divides, and with its fellow is attached 

 to the stomach. The anterior double-bladder closely resembles 



that of the Catastomi (which is followed by two or three ordinary Classifica- 

 Bwim-bladders), belongs to the organ of hearing, and corresponds tign — Ma- 

 to the membranous labyrinth of the higher moUusk". lacopteri, 



Geni'S 1. Gymnotus, Linn. Slan entirehi soft, and deititute of \ ^ -^ / 

 frol'S. Only one species is known, which resembles Carajnis in the 

 conformation of the head, position of the nostrils, and dentition ; 

 but the anal fin reaches the point of the tail. Uead oval, flatly de- 

 pressed; mouth not opening quite as far as under the eyes, fur- 

 nished with broad lips of equal length ; fore nostril a small tube 

 in a bell-shaped superficial depression above and towards the end 

 of the lateral lip; hinder nostril distant about the diameter of the 

 eye from tlie first one, behind and above it. Longitudinal and trans- 

 verse rows of pores in cup-shaped depressions on the top of the 

 head ; also a row on the mandible ; lateral line indicated by a row 

 of distant pores. 



About fifty pointed teeth on the upper jaw, and sixty on the under 

 one ; a second row behind the middle of the upper ones of about six 

 teeth ; along the symphysis of the mandible two short rows, each 

 with two toothlets. Vomer, roof of the mouth, and tongue furnished 

 with lateral, projecting, dentated membranous edgings. Vent be- 

 fore the gill-openings; behind it a small orifice and a small, slen- 

 der papilla. Pectorals and anal fin enveloped in a thick skin which 

 conceals the rays. One species. 



Genus II. C.^rapus, Miill. and Trosch. (Carapus, Cnr . partim.) 

 Broad, depressed, Jiattish snouts a row of pointed teeth; scales. No 

 caudal fin. Fore nostril a short tube in a notch near the corner of 

 the mouth; hinder one before the eye, open and distinct; eyes 

 shining through the skin ; five broad, flat branchiostegals; anal fin 

 extending almost to the end of the tail; under lip longer than the 

 upper one. Scales of the back and lateral line of equal size. Two 

 species. 



GicNus III. Sternopygus, Miill. and Trosch. Card-like teeth 

 in numerous rows; small mouth. Body and head compressed; head 

 short ; small jaws ; occasionally traces of card-like palatine teeth. 

 Tail slenderly prolonged, without a caudal fin. Scales of the lateral 

 line mostly larger than the others. 



This genus has the aspect of a Fierasfer. Four species. 



Fig. 68. 

 Rhamphichthi/s Artedi. 

 Gencs IV. Rhamphichthys, Mull, and Trosch. A small 



mouth ; no teeth ; snout more or less tubularly elongated, and 

 provided with small pores ; nostrils not tubular. Head and body 

 compressed, and with an exception scaly. Anal fin long, but leaving 

 the end of the tail free. 



The species divide themselves into two groups : — • 



1. Snout short; largely developed genital papilla. Anus behind 

 the third part of the head ; and anal fin commencing at the point 

 of the pectoral. Two species. 



2. Anus under or before the eye, and the anal commencing before 

 the gill-opening. Seven species. 



Fig. 69. 

 Sternarchits oxyrkinchus. 

 (tENUS V. SxERNATicnus, Schneid. Having a small normally 

 formed caudal Jin. A crowd of teeth on the pre-maxillaries, and 

 two rows of recurved ones on the mandible ; no tooth on the sym- 

 physis. Head and body laterally compressed, the former naked, the 

 latter scaly. In the middle of the dorsal surface of the tail an elas- 

 tic ray, which, in the living fi=h, lies in a furrow and is kept firmly 

 there by the dermal mucus (this ray is homologous with the fleshy 

 fin of the Salmonidir) ; anus before or under the eye; eye shining 

 through without a lid. Nostrils like small pores. Four branchi- 

 ostegals in the gill membrane. Three species. 



