326 THE REASON WHY : 



" Lie there, Lycaon : let the fish surround 

 Thy bloated corpse, and suck thy gory wound." POPE. 



rudiment of an olfactory organ. The mouth is at the front of the head, -where it 

 forms an oval opening without jaws, but surrounded by a number of cartilaginous 

 points ; the oval cavity leads into a large branchial sac. By the action of cilia, 

 with which these cavities are lined, currents are produced in water, the water 

 passing off through numerous slits in its walls into the general cavity of the bc'dy, 

 whence it escapes by an opening in the ventral surface.* 



ORDER II. CYCLOSTOMATA. 



1040. Why is the second order of fifties called cyclostomata f 



From two Greek words meaning a circle and a mouth, in 

 reference to the circular mouth which distinguishes the members 

 of the order. 



1041. They are of an elongated, cylindric, and worm-like form ; the skin is 

 tough and destitute of scales ; the pectoral and ventral fins are wanting ; the 

 skeleton is cartilaginous ; breathing orifices, little sacs that open exteriorly by 

 separate vents ; heart muscular, composed of two chambers. 



1042. Why has the lamprey a circular, cartilaginous mouth ? 



Because it lives by suction, some species living upon insects and 



worms : others upon the 

 juices of the larger fishes. 

 One species, the hag, con- 

 trives to enter the mouths 

 of fishes, and extracts their 

 S'ibstnnce by sucking. Fish 

 tha have been hooked on 

 Hm s and allowed to remain 

 in the water for some time afterwards, have been attacked by 

 these creatures, and when drawn up have been found to consist 

 of Httle more than empty skin. 



1043. Formerly the lamprey was a fish of considerable importance. It was 

 taken in great quantities in the Thames, and sold to the Dutch as bait for turbot, 

 c<'d, and other fisheries. Four hundred thousand have been sold in one season foi 



Orr's "P'rcle of the Sciences." 



