“Is it alive? It hangs helpless and motionless, a mere velvet string, across the hand. Ask the neighbouring Annelids and the fry of the rock-fishes, or put it into a vase at home, and see. It lies motionless, trailing itself among the gravel; you cannot tell where it begins or ends; it may be a dead strip of seaweed, _Himanthalia lorea_, perhaps, or _Chorda filum_, or even a tarred string. “So thinks the little fish who plays over and over it, till he touches at last what is too surely a head. In an instant a bell-shaped sucker mouth has fastened to his side. In another instant, from one lip, a concave double proboscis, just like a tapir’s (another instance of the repetition of forms), has clasped him like a finger; and now begins the struggle: but in vain. He is being ‘played’ with such a fishing-line as the skill of a Wilson or a Stoddart never could invent; a living line, with elasticity beyond that of the most delicate fly-rod, which follows every lunge, shortening and lengthening, slipping and twining round every piece of gravel and stem of seaweed, with a tiring drag such as no Highland wrist or step could ever bring to bear on salmon or on trout. “The victim is tired now; and slowly, and yet dexterously, his blind assailant is feeling and shifting along his side, till he reaches one end of him; and then the black lips expand, and slowly and surely the curved finger begins packing him end foremost down into the gullet, where he sinks, inch by inch, till the swelling which marks his place is lost among the coils, and he is probably macerated to a pulp long before he has reached the opposite extremity of his cave of doom. “Once safe down, the black murderer slowly contracts again into a knotted heap, and lies, like a boa with a stag inside him, motionless and blest.” The accuracy as well as the pictorial effect of this description cannot be surpassed. The “velvety” feel of the creature is most wonderful, as it slips and slides over and among the fingers, and makes the task of gathering it together appear quite hopeless. This astonishing worm is drawn on the left hand of the illustration on page 93, so as to show the way in which the body is contracted or relaxed at will. On the other side of the illustration is an angler, armed with all the paraphernalia of his craft, and doing imperfectly that which the Nemertes does with absolute perfection. A similar property belongs to the long, trailing tentacles of the Cydippe, which is described and figured on page 16. When they come in contact with suitable prey, all struggle is useless, the tentacles contracting or elongating to suit the circumstances, and at last lodging the prey within the body of the Cydippe. THE SPRING-TRAP. We are all familiar with the common Spring-trap, or Gin, as it is sometimes called.