May 1, 1896.] 



KNOWLEDGE, 



97 



ILLUSTRATED MAGAZINE 



LONDON : MAY 1, 1896. 



CONTENTS. 



The "Walking Goby. 15_v Henry O. Forbes. LL.D. 

 {Illustrated) " 



English Coins.— I. By G. F. Hill, M.A. (Plate) 



Some Curious Facts in Plant Distribution.— II. By 



W. BoTTiNO Hemslev, F.R.S .". 



Our Fur Producers, — III. Foxes, Wolves, and Bears. 

 By K. Ltdekker, B.A.Cantab,, F.R.fS, (Illustrated) ... 



Science Notes 



Variable Stars. By Dr. A. Beestee, Jz 



The Nebulosity round 15 Monocerotis. Br K. 



Walter llArxDEE, F.R.A.S. (Plate) ... ... ' .... 



Notices of Books. (Illustrated) 



Letters:— David E. Hadden ; W. H. S. Uonck ; T. Law 

 AVebe, M.E.C S. ; E. Srowx ; W. H. A. Cowell; W. CJ. 

 BrszAiiD ; Rev. Sami el Barbee ; AT. E. Beslet 



Waves.— V. The Tide Wave. By Tauohax Cornish, 

 II. Sc. (Illustrated) " 



Babylonia and Elam Four Thousand Years Ago. Hv 

 Theo. G. Pi.nches, AI.R.A.S. illlustrated) 



The Face of the Sky for May. By Heebeet Sadlee, 

 F.R.A.S 



Chess Column. By C. B. Looooe, BA.Oxon 



97 



98 



103 



10.3 

 106 

 107 



109 

 109 



THE "WALKING" GOBY. 



By Henry 0. Forbes, LL.D., 

 Director of Mt(si-itms to the Corporation of Liverpool. 



THE naturalist haunting at ebb tide the sca-shons 

 of the Indian or West African tropics, especially 

 where they are muddy, cannot fail to have hi^ 

 attention arrested by a crowd of curious tadpole- 

 like creatures which stampede before him. He 

 will come upon them congregated together in largo num- 

 bers, sitting basking in the hot sun a few inches above 

 the water line, either on soft, muddy flats, or in the 

 mangrove swamps, where they seem to delight to sit upoii 

 the branching rool'< of those trees. On his approach, off 

 they will scamper at a headlong pace by frog-like leap.-), 

 some into the shallow water, others along the shore into 

 safe hiding. If he proceeds, however, very guardedly, he 

 may advance within a short distance of some of them ; he 

 will then perceive that, though enjoying themselves on land, 

 they are true fishes. 



The species \a Perioplitloibdus Iwelrcuteri, the "hopping 

 fish" of the trader, one of the gobies ((iobiidn'). Their 

 tadpole-like look arises from their tapering tail and 

 curiously prominent eyes, which stand up high above the 

 level of the head. It is an elegant little beast, with skin 

 covered with minute scales, and its dorsal lius beautifully 

 spotted with bright blue. If the observer remain quite 

 still, the reriojihihalmux will sit motionless, staring at him 

 with its great eyes, except that every now and then it will 

 wink apparently, sometimes with one eye and sometimes 



with both together. What seems to be winking, however, is 

 the inversion of the eye into a depression immediately under 

 it, for the purpose of lubricating the organ when it begins 

 to become dry. The habit that most impresses the 

 naturalist encountering these fishes for the first time is 

 the long period which they can remain out of the water. 

 The writer has timed individuals, both in their native state 

 and in the aquarium, to sit for more than half an hour 

 without a bath. They would then walk slowly into the 

 water, immerse themselves over the head for a second, 

 emerge and remain resting for a short time, with the 

 head and shoulders above and the mouth under the 

 surface, and walk slowly out again on to the margin. 

 This fish rarely, if ever, goes beyond its depth, and 

 only for a few seconds does it at any time completely 

 submerge itself. Their usual habit is to sit propped 

 up on their stiff ventral and strong pectoral fins, with 

 the fore part of the body elevated, and their quick 

 mobile eyes conspicuous and enquiring ; either, as already 

 remarked, entirely away from the water, or with only the 

 extremity of the tail dipping in. When out of the water 

 and sitting still the mouth is kept closed, and no motion 

 can be detected in the gills or gill- coverts. Every now 

 and then the eyes are moistened as descrilaed above, and 

 the fish flaps its pectoral fins across the gill-coverts and 

 the hind part of the head. When the tide hasjust receded 

 and the small marine animals are beginning to follow it, 

 they are very busy darting here and there in pursuit, and 

 gobbling them up voraciously. They will even attack and 

 eat smaller members of their own species. 



reniijihtliiitmus loelreuleri. — Front view. 



When movingforward they oar themselves on their strongly 

 muscular pectorals, which they use simultaneously when 

 hopping or alternately in their more deliberate "walking." 

 which leaves a curious triple track on the soft mud which 

 they have traversed. When in the water the Perioiiliihalmu.-i 

 sits on the bottom in the same attitude as on shore, with 

 its upper lip submerged, but with the rest of the head and 

 upper part of the back exposed, the water being driven 

 over its gills very slowly and deliberately as compared 

 with the common trout in an adjoining tank. Its eyes are 

 better adapted for sight out of tlian under water, and are 

 capable of seeing all round. They are amazingly quick : 

 the slightest wriggle of a worm or small crustacean, even 

 at several feet distance directly behind them, will be 

 instantly detected, and the creature at once pounced upon — 

 often by more than one at once, in which case a battle 

 ensues, resulting frequently in each combatant carrying 



