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little astonished when told that a fish in the Aquarium, scarce- 

 ly three feet long , is a shark ; and probably imagines it to 

 be a young, or " false " shark, We must therefore remind our 

 reader that the chief characteristic of the species is not gigantic 

 size , but a peculiar organisation ; and that , excluding young 

 ones, there are very small varieties of the species shark, which 

 have all the peculiarity of construction common to the large 

 varieties. In order to understand this peculiarity , as far as 

 visible in the living animal , we beg the visitor to look atten- 

 tively at one of the spotted cat-sharks that usually lie in a cor- 

 ner close to the glass of the large tank, and compare it with 

 one of the large perches. The perch has the typical scaly body> 

 dorsal, pectoral and anal fins, symmetrical tail, large moveable 

 gill-coverings , with the leaves of the gills beneath lying in 

 rows fastened to a bony arch, and mouth situated at the point 

 of the head; it has further lidless and glassy eyes, and small 

 nostrils. The shark, on the contrary, has no scales, but has 

 a rough skin like -chagrine; its tail is unsymmetrical, one side 

 being long, the other short. Its mouth is a large slit, set cross- 

 wise under the head, and its gills are fast grown to the sides 

 of certain pouches which lie one behind the other, and are led 

 to by a row of five or more openings in the skin of the neck. 

 Its eyes have lids which can close, and its large nostrils are 

 distinguished by flaps of skin. The skeleton of the shark is 

 cartilaginous-not bony-and the skull is a gristly capsule. These 

 characteristics are common to all sharks, both large and small, 

 and by them even an unpractised eye at once recognises the 

 genus as entirely different from all bony fishes. 



The shark which m we take for an example , belongs to the 

 genus Scyllium, of which two kinds, the Sc. catulus and 

 the Sc. canicula cat-shark and dog-shark are found all 

 over Europe. The first attains a length of three to three and 

 a half feet , the latter only one and a half to two feet, so that 

 this one belongs to the smallest variety. They are lazy fish 

 which hunt their prey at dusk and in the night, and during 

 the day generally sleep in a corner of the tank, rarely swim- 

 ming about. In the daytime they seek their food by scent, for 

 at that time they are half blind. They go smelling all over the 

 bottom of the tank, with graceful motions of their spotted bodies, 

 and it is only when they touch it with their noses that they find 

 their food. They are little less gluttonous and impudent than 

 their larger relatives, and their well-armed jaws can master im- 

 mense pieces. We have become thoroughly acquainted with their 



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