Proceedings. jg 



and prejing on other animals, or herbivorous, feedin- on 

 plants. ° 



The Vertebrates, then, differ from the Invertebrates in pos- 

 sessmg a long column, generally jointed and bony, extending 

 from then^ head to the end of their tail, and forming a firm 

 support for the attachment of the head and hmbs, and aU 

 other parts of the body. 



_ Thesiinplestformofvertebratewithwhichweareacquainted 

 IS the fish, the Lancelet. This little creature, which is almost 

 transparent, burrows in sand at the bottom of shallow water. 

 The back-bone, or what passes for such, is a continuous 

 cartilagmous or gristly rod, called the "notochord," running 

 from one end of the creature to the other; and there is 

 nothmg which answers to either ribs, skull, or limbs. It has 

 a large oval mouth, fringed with tentacles leading into a large 

 throat or pharynx, which is covered on the inside surface 

 ^vlth yibratmg « ciha." This large throat leads into another 

 chamber, and this again into an intestine along which the 

 food passes Now, on each side of the pharynx there is a row 

 of sh s and as the water is wafted into the pharynx from the 

 mouth by the waving cilia it passes out through these slits 

 into the cavity of the body, and then out again by a small 

 opening ; this represents the breathing-apparatus for purifying 

 the blood. The heart is a very simple affair, a mere [ub^ 

 wnch keeps on expanding and contracting, and so dx-ives the 

 white b ood along the vessels which are in connection with it. 

 borne of these vessels pass up the divisions between the shts 

 and so bnng the blood into near contact with the water which 

 passes through them ; this is a very simple form of gill The 

 spmal marrow or cord is only represented by a thread ofnerve 

 lymg along the upper side of the notochord ; and this is quite 

 simp e, not enlarging into anything like a brain at the head- 

 end, but giving off small nerves to the mouth and to the tiny 

 imperfect eyes. In this simply-made animal we see that a 

 few, and a very few, of the characters of the Vertebrates have 

 their representatives. 



There is another small animal classed with this Lancelet 

 m the lowest division of Vertebrates, and to show that it is 



