248 ANIMAL INTELLIGENCE. 



angler. "We must also allude to the Ghelmon rostratusy 

 which shoots its prey by means of a drop of water projected 

 from the mouth with considerable force and unerring aim* 

 The mark thus shot at is always some small object, such 

 as a fly, at rest above the surface of the water, so that 

 when suddenly hit it falls into the water. ^ This remark- 

 able instinct can only, I think, have originated as a 

 primordially intentional adjustment, and as such shows a 

 high degree of intelligence on the part of these fishes' an- 

 cestors. Moreover, the wonderful co-ordination of sight 

 and muscular movements required to judge the distance, 

 to make due allowance for refraction, and to aim correctly, 

 shows that the existing representatives are not unworthy 

 of their ancestors. 



Several species of fish in difi'erent parts of the world 

 have the habit of quitting pools which are about to dry 

 up, and taking excursions across country in search of more 

 abundant water. Eels have this habit, and perform their 

 migrations by night. Dr. Hancock, in the 'Zoological 

 Journal,' gives an account of a species of Boras, the indi- 

 viduals of which are about a foot in length, and travel by 

 night in large shoals, or ' droves,' when thus searching for 

 water. A strong serrated arm constitutes the first ray of 

 the pectoral fin; and, using this as a kind of foot, the animal 

 pushes itself forward by means of its tail, thus moving 

 nearly as fast as a man can walk. Another migrating fish 

 (^Hydrargzra) was found by thousands in the fresh waters 

 of Carolina by Bosc. It travels by leaps, and, according 

 to Bosc, always directs itself towards the nearest water, 

 although he purposely placed them so that they could not 

 see it. 



But perhaps the strangest among this class of habits 

 is that of the climbing perch {Perca scandens), first dis- 

 covered by Daldorff in Tranquebar; for this animal not 

 only creeps over land, but even climbs the fan palm in 

 search of certain Crustacea which form its food. In climb- 

 ing it uses its open gill-covers as hands wherewith to- 

 suspend itself, while it deflects its tail laterally upwards so< 

 as to bring to bear upon the bark certain little spines with 



1 See ' On the Jaculator-Fish,' by Schlosser, Phil. Trans. 1764. 



