348 



- KNOWLEDGE ♦ 



[Dec. 7, 1883. 



THE LANCELET FISH. 



THE lancelet (Amphioxus lanceolatus) has so little 

 similarity to other members of the fish family that 

 for a long time it was undecided whether it belonged to the 

 vertebrate or invertebrate class. Its body is about five 

 centimetres long, slender and angular, symmetrically taper- 

 ing off to a point at each end. A slender fin extends from 

 the head around the extremity of the tail and terminates at 

 the vent. The mouth, a mere longitudinal fissure, is under 

 the front part of the body, and its orifice is crossed by 

 numerous cirri. This fish has no heart, the place of that 

 organ being taken by tubular vessels having a pulsating 

 motion, which drives the transparent colourless blood into 

 the smaller veins. It has no bones, the muscles being 

 attached to soft cartilage, and the spinal cord is not pro 

 tected by a bony covering. The body is covered by a 

 delicate skin without scales. It is found in the seas of the 

 torrid and temperate zones. It lives in the sand, in which 

 it buries itself, and being so nearly the colour of the sand, 

 it is completely concealed, and is often only perceived when 

 the sand is washed through a fine meshed sieve. Probably, 

 ■wherever it makes its appearance it is far more abundant 

 than is generally supposed. If it is necessary for it to 

 leave the sand, it swims through the water with a gliding, 

 serpent-like motion, and with the quickness of an arrow, 

 but in a short time it embeds itself again in the sand. Mr. 

 Couch was the first captor of this fish on the British coast, 

 and found his first specimen in the sand about fifty feet 

 from the receding tide. He says that when swimming the 

 head can hardly be distinguished from the tail. 



Mr. Wilde put one of these fish in a tumbler of water. 

 " It moved round the glass like an eel, and, although no 

 eyes were perceptible, it avoided the finger or any sub- 

 stance put in its way, stopping suddenly or turning aside 

 from it." The mouth is surrounded by cilia, the motion 

 of which causes the passage of water for food and for 

 breathing. 



THE STAE-NOSED MOLE.* 



THE star-nosed mole is strictly an American animal, and 

 its genus is confined to America alone. Its great 

 peculiarity lies in the strange formation of its nose — or, 

 rather, its nasal appendages. The muzzle, which is a kind 

 of cartilaginous disc, sending out about twenty fibres or 

 feelers, when viewed from the front has the appearance 



The Star-Nosed Mole. 



of a star, hence the common name " star-nosed." The two 

 cartilaginous fibres situated beneath the nostrils are the 

 shortest. The use of this radiating process has not been 

 fully ascertained, but it is quite probable that it is ex- 

 tremely sensitive, and is used for detecting the presence of 

 its prey. It always touches or feels an object with this 

 " star " before swallowing it 



The star-nose is subterranean in its habits, and rarely 

 quits the ground, at least during the day, and hence it is 

 seldom seen. It is generally found in moist^valleys along 



The Lancelet Fish. 



These fish have a peculiar and remarkable power of 

 attaching themselves to each other, sometimes clustering 

 together, sometimes forming a string from fifteen to twenty 

 centimetres long. In the latter case they swim in unison, 

 with a serpent^like motion. When swimming in a line 

 they adhere to each other by their fiat sides, the head of 

 one coming up about one-third on the body of the one 

 before it, as seen in the engraving. — From Brehm's Animal 

 Life. 



the banks of streams, and consequently do3S not damage 

 gardens and lawns by digging furrows through them, like 

 the common mole. Its food consists of earth-worms, and 

 the grubs of beetles, cicada?, and other ground-dwelling 

 insects. In captivity it will eat raw meat of any kind. 



During the breeding season the tail of ti.e star-nose 

 becomes greatly enlarged, and this form has been described 



* From Scientific American. 



