346 THE REASON WHY : 



And over all with scales was arm'd, 



Like plated cote of steele, so couched neare 



That nought mote perce." SPENSER. 



Sub-order VI. Plectognatha. 

 1118. Why is the sixth sub-order termed plectognatha ? 



From plecto, to connect, and gnathos, a jaw signifying that 

 the bones of the upper jaw and palate are connected with those 

 of the cranium. 



1119. The head is large, the mouth small, and the gills so covered with skin and 

 muscles that only a small aperture is left for the exit of water employed in respira- 

 tion. The body is usually short and stout, and covered with a thich rough skin, or 

 sometimes with bony plates. 



1120. Why is the trunk-fish covered with a complete suit of 

 bony plates ? 



These plates furnish to the trunk-fish a coat of armour analogous 



to that worn by the arma- 

 dillo, and doubtless for 

 similar purposes. The body 

 is covered with plates, so as 

 to form a perfect coat of 

 armour, leaving only the tail, 

 fins, mouth, and a small 

 portion of the gill-opening, capable of motion, all of which move- 

 able parts pass through openings of the armadillo-like coat of mail, 

 the joints being protected and rendered flexible by a leathery 



substance. 







ORDER IV.-GANOIDEA. 



1121. Why is the fourth order of fishes named ganoidea? 



From ganos, splendour, and edios, appearance. Of the remark- 

 able fishes belonging to this order, very few exist at present in our 

 waters. But their fossil remains occur in abundance in almost all 

 (he fossiliferous strata of the earth. They are divided into two 

 mb-orders : 



