38 MARINE ANIMALS OF MASSACHUSETTS BAY. 



found to have lost about ff$ of its original weight, only the 

 merest film remaining on the paper upon which it had been laid. 

 The prominence of the disk in this group of Jelly-fishes is well 

 characterized by their German name, " Scheiben quallen," viz. 

 disk-medusae. We shall see hereafter that the disk, so large and 

 seemingly solid in the Discophorae, thins out in many of the other 

 Jelly-fishes, and becomes exceedingly concave. This is especially 

 the case in many of the Hydroid Medusae, where it assumes a 

 bell-shaped form, and is constantly spoken of as the bell. It 

 should be remembered, however, in reading descriptions of these 

 animals, that the so-called bell is only a modified disk, and per- 

 fectly homologous with that organ in the Discophorae. 



The Discophorous Medusae are distinguished from all others by 

 the peculiar nature of the reproductive organs. They are con- 

 tained in pouches (Fig. 50, 0,0,0,0), the contents of which are 

 first discharged into the main cavity, and then pass out through 

 the mouth. Pillars support the four angles of the digestive 

 cavity, thus separating the lower from the upper floor of the disk, 

 while the chymiferous tubes (Fig. 50) branch and run into 

 each other near the periphery, forming a more or less compli- 

 cated anastomosing network, instead of a simple circular tube, as 

 is the case with the Hydroid Medusae. (Fig. 74.) 



Cyanea. (Cyanea arctica PER. et LES.) 



In our descriptions of the Discophorae, we may give the pre- 

 cedence to the Cyanea on account of its size. This giant among 

 Jelly-fishes is represented in Fig. 44. It is much to be regretted 

 that these animals, when they are not so small as to escape atten- 

 tion altogether, are usually seen out of their native element, 

 thrown dead or dying on the shore, a mass of decaying gelatinous 

 matter. All persons who have lived near the sea are familiar 

 with the so-called Sea-blubbers, sometimes strewing the sandy 

 beaches after the autumn storms in such numbers that it is diffi- 

 cult to avoid them in walking or driving. In such a condition 

 the Cyanea is far from being an attractive object ; to form an 

 idea of his true appearance, one must meet him as he swims 

 along at midday, rather lazily withal, his huge semi-transparent 



