60 MARINE ANIMALS OF MASSACHUSETTS BAY. 



toward its lower margin, leaving open the circular aperture called 

 the mouth ; this narrowing of the membrane is produced by a 

 number of folds in its lower part, while at its margin these folds 

 spread out to form ruffles around the edge of the mouth, and 

 these ruffles again extend into the long scalloped fringes hanging 

 down below. 



The motion of these Jelly-fishes is very slow and sluggish. 

 Like all their kind, they move by the alternate dilatation and 

 contraction of the disk, but in the Zygodactyla these' undulations 

 have a certain graceful indolence, very unlike the more rapid 

 movements of many of the Medusae. It often remains quite mo- 

 tionless for a long time, and then, if you try to excite it by dis- 

 turbing the water in the tank, or by touching it, it heaves a slow, 

 lazy sigh, with the whole body rising slightly as it does so, and 

 then relapses into its former inactivity. Indeed, one cannot help 

 being reminded, when watching the variety in the motions of the 

 different kinds of Jelly-fishes, of the difference of temperament in 

 human beings. There are the alert and active ones, ever on the 

 watch, ready to seize the opportunity as it comes, but missing it 

 sometimes from too great impatience ; and the slow, steady peo- 

 ple, with very regular movements, not so .quick perhaps, but as 

 successful in the long run ; and the dreamy, indolent characters, 

 of which the Zygodactyla is one, always floating languidly about, 

 and rarely surprised into any sudden or abrupt expression. One 

 would say, too, that they have their aristocratic circles ; for there 

 is a delicate, high-bred grace about some of them quite wanting 

 in the coarser kinds. The lithe, flexible form of the greyhound 

 is not in stronger contrast to the heavy, square build of the bull 

 dog, than are some of the lighter, more frail species of Jelly-fish 

 to the more solid and clumsy ones. Among these finer kinds we 

 would place the Tima. (Fig. 76.) 



Tima. (Tima formosa AG.) 



One's vocabulary is soon exhausted in describing the dif 

 ferent degrees of consistency in the substance of Jelly-fishes. 

 Delicate and transparent as is the Tima, it has yet a certain 

 robustness and solidity beside the Oceania, described above. In 



