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SCIENTIFIC NEWS. 



[Nov. 9, 1888. 



character. This structure is especially noticeable in the 

 Onychoteuchis. 



And there is another point connected with these addi- 

 tional tentacles which must not be overlooked, for each 

 is provided with a small group of adhesive discs of the 

 ordinary character. And for this reason : Sometimes a 

 victim is seized which, although it cannot break away 

 from the hook-armed suckers, yet struggles so violently 

 that it cannot be drawn sufficiently near to the body for 

 the employment of the beak. In such cases both the 

 long tentacles are brought into use, and, adhering closely 

 together by means of the simple sucking-discs at their 

 extremities, supplement one another, just as we ourselves 

 employ both arms to drag to us an object which neither 

 alone is sufficiently strong to move. And after the 

 victim has been drawn up for a little distance, the shorter 

 tentacles also are employed, and its doom thus sealed. 



These singular suckers — those of the simple kind, that 

 is — combine in themselves all three of the functions 

 referred to at the commencement of this paper, for not 

 only are they employed as weapons, and weapons of the 

 most formidable character, but they are also used both in 

 locomotion and as anchors by which their owner may 

 cling to a rock or stone. 



What the precise function of the sucking-disc of the 

 Remora (Eckeneis remora) may be is still altogether 

 unknown ; but it is nevertheless a most singular piece of 

 mechanism. Lying on the upper surface of the head, it 

 consists of a number of flat, bony lamina;, arranged side 

 by side very much after the manner of the laths of a 

 Venetian blind, and capable of being raised or depressed 

 at the will of their owner. The edge of the disc itself is 

 soft and fleshy, and when this is placed in contact with 

 any smooth surface, and the lamina? are depressed, a 

 vacuum is formed, causing the fish to adhere so tightly 

 to its hold that scarcely any amount of force will detach 

 it. In this manner the fish will affix itself to whales, 

 turtles, sharks, and many other of the larger inhabitants 

 of ocean, being carried by them for immense distances 

 through the water, apparently in total ignorance of its 

 presence. 



This strange sucking organ would appear to be a 

 modification of the first dorsal fin, the bony laminae by 

 which the vacuum is caused exactly corresponding in 

 number to the spines. But as regards the object of its 

 presence we are altogether in the dark. It cannot be 

 merely an aid to locomotion at the expense of other fish, 

 etc., for the remora is a good swimmer, and is at least as 

 swift and active as are many of its fellows ; and there 

 seems to be no reason why it should wish to pass 

 through the water with unusual speed. Nor does it 

 appear to find any difficulty in procuring food, for when 

 a specimen is killed and examined its stomach is nearly 

 always full. Possibly the disc is employed as a means 

 of defence, the fish attaching itself, when in danger, to 

 some creature of far greater size, and thus putting itself, 

 as it were, under protection. We do not know. One 

 would think, from its highly developed condition, that the 

 organ in question must have some special function, but 

 of what nature that function may be has so far passed 

 the wit of man to ascertain. 



The Discoboli, or quoit-fishes, are provided with a 

 somewhat similar sucker upon the ventral surface of the 

 body, formed by a modification of the ventral fins, and 

 capable of holding so firmly that one of these fishes 

 which had affixed itself to the bottom of a pail of water 

 still retained its hold when lifted by the tail, though it 



was consequently obliged to sustain the weight both ot 

 the pail and the water. The ventral fins of the gobies 

 are modified in very much the same manner. 



The lamprey possesses an excellent sucking organ in 

 its mouth, and employs it not only for mooring purposes 

 when the current is strong, but also for removing stones, 

 etc., from the spot in which it wishes to lay its 

 eggs. And the leech, although so widely removed in 

 the zoological scale, has a mouth of very similar chaiacter, 

 but armed with teeth capable of penetrating the skin ol 

 any animal to which it may affix itself. 



The suckers upon the foot of the gecko, which termi- 

 nate each of the toes, are employed solely as aids to 

 locomotion, enabling their owner to ascend a perpendi- 

 cular wall, or to creep head downwards across a ceiling, 

 with perfect ease and safety. And thus the animal is 

 able to capture its insect victims under conditions which 

 would place them in almost absolute safety from all 

 other foes. Something of the same kind we find in the 

 feet of the house-fly and its allies, but in these true 

 suckers are wanting, and the flat disc of the foot adheres 

 to a wall or ceiling merely by reason of a strongly 

 glutinous fluid which it secretes ; and, as the feet are 

 lifted obliquely, they can be removed from their hold 

 without the slightest difficulty. 



Quite an array of true suckers, however, we find in 

 the anterior feet of the male great water-beetle (Dyticus 

 marginalis). These are of two kinds, two large ones 

 being situated upon the foot itself, while the re- 

 mainder, which are very numerous and much smaller, 

 are set at the extremities of slender foot-stalks, and 

 look something like inverted mushrooms. Upon the 

 intermediate feet, also, there are a few of these suckers, 

 although the basal joints of the tarsi are not swollen into 

 large fleshy pads, as are those of the front pair. In the 

 female insect they are altogether wanting. 



Finally, we have examples of the sucker structure 

 in the bases of sea-anemones, by means of which they 

 attach themselves to rocks, and also in the "feet" of 

 to such molluscs as the limpet, which can cling so firmly 

 their hold that it is very difficult indeed to remove them. 

 It will be noticed that in the great majority of cases 

 these natural suckers are possessed by aquatic creatures, 

 to which they would obviously prove more useful than 

 to those living upon dry land ; for the employment of a 

 sucker under water signifies not only the atmospheric 

 pressure of fifteen pounds upon the square inch ot 

 surface, but also the pressure caused by the water itself. 

 And it also follows that the greater the depth at which 

 they are employed, the greater the force involved. Thus 

 the cuttle fish is able to hold creatures which in the air 

 above would easily break away, and the remora to with- 

 stand force which, were it lifted from the water, would 

 suffice easily to drag it from its hold. But the suckers even 

 of such creatures as the gecko are tolerably powerful, and 

 cannot be detached save at the expense of some little 

 force. 



Edible Birds' Nests. — Mr. Steere, a traveller in the 

 Philippine Archipelago, in the course of a paper in the 

 American Naturalist, descriptive of the central islands 01 

 the group, refers to certain caves in the Island of Gui- 

 maras where edible birds' nests are found. The bird 

 which builds these nests is a species of swallow or swift, 

 and the caves are not found opening on the sea, but far 

 inland where the cavities are covered by vegetation. 

 Guided by an old Indian whose livelihood was obtained 



