628 THE MANTIS SHRIMP. 



appendages near the tail seem to be merely used for the purpose of cleaning its bur- 

 row of wood, dust which is not required for food. The creature always swims on its 

 back, and when commencing its work of destruction, clings to the wood with the legs that 

 proceed from the thorax. The Wood-boring Shrimp is one of the jumpers, and, like the 

 sand-hopper, can leap to a considerable height when placed on dry land. 



Another wood-boring shrimp will be figured and described in a succeeding page. 



ON the left hand of the illustration are seen two figures of a crustacean called 

 appropriately the SKELETON-SCREW, or MANTIS-SHRIMP. There are several species 

 belonging to this genus, and all possess similar habits. Their bodies are indeed 

 skeleton-like in their bony lankness, but their appetites are by no means small in pro- 

 portion to their size. Indeed, as is often the case with peculiarly meagre human beings, 

 they are most voracious, preying incessantly on every small creature that comes in their 

 way. They are furnished with terrible instruments of prehension, their first and second 

 pairs of legs being devoted wholly to this purpose. The last joint but one is enormously 

 large, and the last joint is thin, and shuts down like the blade of a clasp-knife into its 

 haft, the groove being represented by a double row of spines between which the blade is 

 received. The blade itself is finely notched along the edge. These claw-like termi- 

 nations to the legs are used not only for seizing prey, but for grasping the branches 

 and drawing the long attenuated body from one part to another. 



Mr. Gosse, who has paid much attention to these curious beings, remarks that their 

 movements among the marine vegetation are wonderfully like those of the spider mon- 

 keys among the branches, their long thin bodies adding to the resemblance. They run 

 about with great agility, and are always to be found in the branches of the Plnmatella 

 cristata. The same writer has given a very interesting history of the Mantis-shrimp : 



" Their manners are excessively amusing. The middle part of their long body is desti- 

 tute of limbs, having instead of legs two pairs of oval clear vesicles, but the hinder 

 extremity is furnished with three pairs of legs armed with spines, and a terminal hooked 

 blade like that already described. With these hindermost legs the animal takes a firm 

 grasp of the twigs of the polypidom, and rears up into the free water its gaunt skeleton of 

 a body, stretching wide its scythe-like arms, with which it keeps up a see-saw motion, 

 swaying its whole body to and fro. Ever and anon the blade is shut forcibly upon the 

 grooved haft, and woe be to the unfortunate infusorium, or mite, or rotifer that comes 

 within that grasp ! The whole action, the posture, figure of the animal, and the structure 

 of the limb, are so closely like those of the tropical genus Mantis among insects, which 

 I have watched thus taking its prey in the Southern United States and the West Indies, 

 that I have no doubt passing animals are caught by the crustacean also in this way, 

 though I have not seen any actually secured. 



The antennae, too, at least the inferior pair, are certainly, I should think, accessory 

 weapons of the animal's predatory warfare. They consist of four or five stout joints, 

 each of which is armed on its inferior edge with two rows of long stiff curved spines, 

 set as regularly as the teeth of a comb, the rows divaricating at a rather wide angle. 

 From the sudden clutching of these organs, I have no doubt that they too are seizing 

 prey; and very effective implements they must be, for the joints bend down towards 

 each other, and the long rows of spines interlacing must form a secure prison, like a 

 wire cage, out of which the jaws probably take the victim, when the bending in of the 

 antennae has delivered it to the mouth. 



But these well-furnished animals are not satisfied with fishing merely at one station. 

 As I have said above, they climb nimbly and eagerly to and fro, insinuating themselves 

 among the branches, and dragging themselves hither and thither by the twigs. On a 

 straight surface, as when marching (the motion is too free and rapid to call it crawling) 

 along the stem of a zoophyte, the creature proceeds by loops, catching hold with the 

 fore limbs, and then bringing up the hinder ones close, the intermediate segments of the 

 thin body forming an arch, exactly as the caterpillars of geometric moths, such as those 

 for example that we see on gooseberry bushes do. But the action of the crustacean is 



