The Zoologist — February, 1874. 3875 



tropical butterflies, gliding along with the smooth action charac- 

 teristic of the Vanessa tribe. Yet a third property of motion is 

 possessed by these remarl<able fish. Settling on the ground at 

 the bottom of the water, they are capable of literally walking 

 over it by means of the three free rays of the pectoral fins, 

 which are situated a little in advance of the others, and are 

 curved and especially thickened, to adapt them for their ano- 

 malous office. 



The gerameous dragonet {Callionymus lyra), a small and beautiful 

 fish somewhat resembling the gurnards in outward appearance, is 

 distinguished by an essentially different mode of progression. The 

 habits of this species are rather sluggish ; it spends much time 

 reclining on the ground, occasionally moving for short distances 

 just above its surface, by the flitting action of the delicate pectoral 

 fins. On ascending towards the top of the water, its swimming 

 capacities are shown to be very limited, being restricted to the 

 weak vibrations of the pair of fins above mentioned, and which 

 impart to it a peculiar jerky action. The male in this species is 

 recognized by the extraordinary length of the first ray of the anterior 

 dorsal fin, which is raised and depressed at pleasure like the latteen 

 sail of a Mediterranean fishing-yawl. This singular appendage 

 appears, from my own observations of the species in confinement, 

 to be subservient to the same end as the wattles, crests, and other 

 abnormal adjuncts of the male in the Gallinaceous birds — for the 

 purpose of fascinating their males j to this is added a similar 

 heightening of the colour, which is carried to such an extent in 

 this fish that the two sexes were long regarded and described as 

 separate species, under the respective titles of Callionymus lyra 

 and dracunculus. 



In the pipe-fish and sea-horses {Syngnathus and Hippocampus), 

 representatives of the Lophobranchii, the organs of locomotion are 

 reduced to their minimum, being often restricted, in the former 

 genus, to a single median dorsal fin, and being at the most supple- 

 mented by a pair of diminutive pectorals and a rudimentary caudal. 

 In all cases this dorsal fin is the chief propelling instrument, and in 

 motion, rapidly undulating from end to end, illustrates the action of 

 the Archiraedian screw, driving the fish through the water on the 

 same principle. Dr. J. E. Gray was the first to point out this 

 remarkable peculiarity, in the case of Syngnathus, from observing 

 these fish in the aquarium at the Zoological Gardens. In both 



