OF THE BRITISH ISLANDS. 21 



of dark and palest blue ; these fins vying, as a whole, in 

 brilliancy with the resplendent wings of the most gorgeous 

 tropical butterflies. To see this remarkable colouring to its 

 greatest advantage, it is requisite to look upon these fish 

 vertically through the water ; and no more interesting 

 and attractive adjunct to a marine aquarium could be in- 

 troduced than a shallow salt-water pond, exposed to the 

 full light of day, devoted to the exhibition of the various 

 members of the Gurnard tribe. The remarkable leg-like 

 conformation of the elements of one portion of the pectoral 

 fin, and the wing-like aspect of the other, is well illustrated 

 in the spirit-preserved example (No. 23a) of the Streaked 

 Gurnard {Trigla lineatd). The remaining British members 

 of the genus Trigla are the red Cuckoo Gurnard (T. cuculus), 

 No. 24 ; the common Grey Gurnard (T. gumardus), 

 No. 26; the Piper Gurnard (T. lyrd); and the Lanthorn 

 Gurnard (T. obscurd). Many of the Gurnards possess the 

 faculty of emitting a dull croaking sound, both beneath 

 and immediately after being taken out of the water, said to 

 be caused by the forcible ejection of gas from their air- 

 bladder by a duct which communicates with the gullet With 

 reference to this peculiarity, the common or Grey Gurnard 

 is distinguished in Scotland by the title of the " Crooner," 

 or " Croonach," a derivative from the Gaelic verb " croon " 

 to croak. Gurnards of the largest size measure as much 

 as or even over two feet, but from one foot to eighteen 

 inches is the more average adult length of our British 

 species. Preserved examples of nearly all our indigenous 

 forms will be found in the Day Collection. 



FAMILY VI.— Mailed Gurnards (Cataphracti). 



Body elongated, sub-cylindrical or angular, invested with a 

 complete cuirass of keeled osseous scales or plates ; the 



