380 THE MICROSCOPE. 



to which the greater portion of the soft parts of the animal 

 are attached, is more deeply furrowed ; and plicse or folds 

 of the mantle fit accurately into the furrows, from which 

 they can easily be removed by the application of a gentle 

 force. The concentric markings have in all cases small 

 scalloped edges; they occur at certain regular intervals, 

 and are so many indications of the lines of growth. In 

 the centre there is a circular depression ; and between its 

 circumference and that of the first concentric marking, 

 there are eight flattened radii. If the under- surface be 

 examined with a power of 100 linear, the ridges will all be 

 found to have small jointed tubular processes like hairs 

 projecting from them. In no part of this horny tissue is 

 there a trace of a cellular or a reticular structure. 



Wonderfully beautiful as are these creatures in form 

 and colour, the amount of solid matter contained in their 

 tissues is incredibly small. The greater part of their sub- 

 stance appears to consist of a fluid, differing little, if at all, 

 from the sea-water in which the animal swims ; and when 

 this is drained away, so extreme is the tenuity of the 

 membranes which contained it, that the dried residue of a 

 jelly-fish, weighing two pounds, wliich was examined by 

 Professor Owen, weighed only thirty grains. The trans- 

 parency of the tissues render the whole of the Acalephce 

 delightful objects for the microscope. 1 



ANNULOiDA. 2 EchinidcB are found in abundance upon 



(1) See an excellent paper in the Transactions of the Microscopical Society, 

 11 On the Anatomy of Two Species of Naked-eyed Medusae," by G. Busk, Esq.; 

 also Professor Forbes' works on this family. 



(2) Description of our Frontispiece. The Aquarium. 

 ASTEROIDS. 



a, Astrophyton scutatum. 

 n, Ophiocoma rosula. 



NUDIBRANCHIATA GASTKOPODA. 



b, Doto pinnatifida back and side view. 



ACALEPHJE. 



c, JEquorea Forbesina. 



d, Medusce Bud. 



e, Thaumantias corynetes. 

 h, Cydippe pileus. 



ECHINOIDE.E. 



/, Echinus, Young Sea-Urchins. 

 g, Echinus sphccra. 



TUNICATA. 



j, AscidicB. 



k, Botryllus violaceus, clustering on the surface of & Fucus. 

 CRUSTACEA. 



I, Corystes cossivelaunus. 



m, Eurynome aspera. 



o t Pagurus Prideauxii, Hermit Crab. 



p. Ebalia Permantii. 



