THE BAFFIN'S BAY ARCTURUS. 477 



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 antennse 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 the 

 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 metric moths, such as those, for example, that we see on gooseberry 

 bushes do. But the action of the crustacean is much more energetic than that of the 

 caterpillar. Indeed, all its motions strike one as peculiarly full of 

 vigor and energy. 



"I have seen the large red species swim, throwing its body into a 

 double curve like the letter S, with the head bent down, and the hind 

 limbs turned back, the body being in an upright position. It was a 

 most awkward attempt, and though there was much effort, there was 

 little effect." In our illustration the creature is enlarged. 



The WHALE-LOUSE is, like all the species of this genus, parasitic, 

 residing on the whale and dolphin. Their hooked and diverging legs, 

 armed with their sharply-curved claws, enable them to cling so tightly 

 that not even the swift movement through the water, or the active WHALB ~ L ^ K Ovamu ' 

 exertions of the creature on which they reside, are sufficient to shake 



them from their hold. The different species of Whale-louse seem to prefer various parts of the 

 body, one species clinging to the head, another to the side, and another to the fin. They all 

 burrow rather deeply into the rough and thick skin of these marine mammalia. 



Their bodies are flattened and rather oval ; they have five pairs of legs, all prehensile ; 

 and on the second or third joint of the thorax, instead of legs there are long appendages for 

 respiration, which usually are bent over the back. The illustration is of natural size. 



ISOPOD A. 



IN the Isopod Crustacea, the signification of which word has already been given, there is 

 a great resemblance to the common wood-louse, and many of them might easily be mistaken 

 for those common and destructive beings. The females have large horny plates on their legs, 

 so formed as to produce a large pouch under the thorax, wherein the eggs are contained. In 

 many species some of the rings of the abdomen are connected so as to resemble a single joint. 



The BAFFIN'S BAY ARCTURUS is one of the best developed of the whole order. In all the 

 species belonging to this genus the body is long, and the first four pairs of legs are beautifully 

 feathered at the ends. These cannot be used for walking, the three last pairs of legs being 

 devoted to this purpose. The long antennae are used as organs of prehension, and with them the 

 creature captures its prey. The young are said to cling by their legs to the antennse of the parent. 



