OF THE BRITISH ISLANDS. 143 



Manchester tanks were accustomed to take their food quite 

 leisurely from their keeper's hand. The entire absence of 

 cirrhose appendages or barbels upon the lower jaw readily 

 distinguish the Grey Mullets from the members of the 

 true Mullets or Surmullets, family Mullida, previously 

 described. 



FAMILY XXVI. STICKLEBACKS (G aster osteidce). 



Body elongated, compressed, scaleless, but more or less 

 protected by bony scutes ; the mouth cleft oblique ; teeth 

 villiform, opercular bones unarmed ; the first dorsa) fins 

 composed of isolated spines, ventral fins articulated with 



FIG. 14. THREE-SPINED STICKLEBACK (Gasterosteus acukdtus). 



the pubic bones, each consisting usually of one spine and 

 one soft ray ; branchiostegal rays three in number ; air- 

 bladder present. 



The Stickleback family includes some half-a-dozen 

 known species of small-sized fish, distributed throughout 

 the Arctic and Temperate regions of the northern hemi- 

 sphere. All of these are referable to the same genus 

 (Gasterosteus), and are, with one exception, naturally inhabi- 

 tants of fresh water, but at the same time susceptible of 

 acclimatisation in brackish and even salt water. Of the 

 three British species the commonest and most familiar type 

 is the three-spined Stickleback (Gasterosteus aculeatus\ No. 

 89, abundant in almost every canal, pond, or stream in the 



