244 INTRODrCTION TO ZOOLOGY. 



seven feet ten inches in length. These fish visit the shores of 

 the Mediterranean in great shoals, and give origin to an exten- 

 sive and valuable branch of commerce. 



Both the species just mentioned swim near the surface, 

 are great consumers of oxygen, and maintain a high temper- 

 ature. The Tunny is always spoken of by the fishermen of 

 the Mediterranean as warm-blooded ; and Dr. Davy* mentions, 

 that he has known the temperatui-e of the Bonito to be 99°, 

 when the water at the surface of the sea was only 80°'5. We 

 have here, therefore, a curious example of a fish with blood as 

 warm as that of a man. 



Highly prized though of so much smaller dimensions, is the 

 Mackerel (Scomber scomber) of our own shores. Mr. Yarrell 

 states that the success of this fishery, in 1821, was beyond all 

 precedent. "The value of the catch of sixteen boats from 

 Lowestofie, on the 30th of June, amounted to £5,252 ; and it 

 is supposed that there was no less an amount than £14,000 

 altogether reahzed by the owners and men concerned in the 

 fishery of the Suffolk coast." A favourite bait for this fish is 

 a slip of red leather or scarlet cloth ; and a scai'let coat has 

 therefore been called a Mackerel bait for a lady. 



Sparidce. — The sea Breams are furnished with strong jaws, 

 and a great profusion of rounded teeth, by means of which 

 they grind down the shells of the mollusca on which they 

 feed. The Stickle-back (Gasterosteus, Fig. 187), and the 

 Gurnard (Trigid), exhibit a peculiarity of a different kind. 

 The head appears as if mailed or armed, and hence the term 

 Loricati, indicating tliis peculiarity, is that by which they are 

 distinguished. The species known as the " Fifteen-spined " 

 (ante, p. 214), inhabits the sea, and is apparently fond of 

 coming to the surface in fine weather, for we have taken it in 

 a small towing-net, and on one occasion we saw it captured 

 by a sudden plunge of the hand into the water. The Gur- 

 nards emit a peculiar sound when taken from the water ; and 

 hence one of them bears the appellation of "the Piper," and 

 another that of the " Cuckoo Gurnard." f 



The Dactyloptei-us of the Mediterranean ( Trigla volilans, 



* Researches, Philosophical and Anatomical. 



f The "Drum-fish" of the I'liited States is so called from its loud 

 drumming noise. It is sometimes found three feet in length, and 35 lbs. in 

 Aveight : in calm weather the sound which it emits is heard at a considerable 

 distance. 



