!)() r.-irl. .second. 



Almost all sharks are viviparous , so that Scyllium is an exception 

 to the rule. 



The Smouth hound or Ray-toothed Shark , Mustelus (Fig. 60) , is 

 only rarely to be seen in the Aquarium. This in one of the most harm- 

 less of sharks ; its blunt flat-topped teeth are not fitted for devour- 

 ing anything but crabs and mollusks, which it captures at great depths. 

 When placed in tank Nr. 10, it swims about at first in a very lively 

 manner with most graceful movements of its glossy body , but it soon 

 tires, and finally cannot lift itself from the bottom of the tank; nor will 

 it touch any food in captivity. Its flesh is quite good eating. 



The Angel-fish or Squatina (Fig. 63) , which forms a connecting 

 link between the Sharks and the Rays , is an unsightly beast , always 

 lying on the bottom of tank Nr. 10, and usually looked upon as dead by 

 the visitors to the Aquarium. It is one of the most stupid and lazy fishes 

 of the Mediterranean, and feeds on fishes frequenting like itself the muddy 

 bottoms of the sea. Its very indiiferent flesh is eaten by poor people, its 

 rough skin is used for graters, sheaths for knives, and other purposes. 



The true Rays have a flat body compressed from above, which has 

 on its upper darker surface the eyes and two openings leading to the 

 gills. On the lower paler surface are situated the mouth, the nasal aper- 

 ture and the gill-slits. They are all dep-sea species and live on the 

 smaller animals frequenting the bottom of the sea. 



The most interesting kind is the Electric Ray, Torpedo (Fig. 65, 

 tank Nr. 12), which was known to the ancients for its strange power of 

 giving electric shocks. Its slimy body is almost circular in shape and 

 contains two large electric organs . Each of these consists of several 

 hundreds of hexagonal columns of a gelatinous substance, which are sup- 

 plied by a number of branching nerves with curious terminations. These 

 organs give rise to a strong electric current when the animal is irritated; 

 this can be demonstrated with a telephone or a small electric lamp which 

 glows at every discharge. 



To experience the whole shock, the fish must be touched at the same 

 time on both sides. The shock is not so strong as that of the South 

 American Electric Eel , but is still sufficiently painful in an adult Ray. 

 The shocks become feeblest when repeated frequently. The electric 

 organ is used both defensively by the Torpedo and also for killing or 

 at least numbing its prey. A young specimen is always kept in a small 

 open tank, in front of tank Nr. 10, for visitors to try the electric power 

 of the fish. - The Electric Ray is one of the most common fishes of 

 the Bay of Naples and in spite of its poor flesh is often brought to 

 market. They bring forth living young ones, 8 14 at a time. The very 

 young embryos have still the shape of sharks and only later on become 

 flattened and disk-shaped. 



Of the other Rays the Skate , Raja (Fig. 69) , and the Sting-ray, 

 Trygon (Fig. 62) , are found in the Aquarium , but the latter more 

 rarely. The former have a lozenge-shaped body of brown colour , and a 

 tail armed with a number of small spines. They lay their eggs in 

 capsules, which are cast ashore on the beach of the North Sea and are 

 called Skate-barrows. The Sting-raye are of dark violet colour and have 



