SPONGES, ZOOPHYTES, AND SEA-FIRS. 47 



margin, leaving only a central hole. This shelf is called 

 the veil, or velum. From the margin of the bell, or 

 umbrella as it is often called, long tentacles project, the 

 number varying in different forms. At the base of the 

 tentacles, or between them, are placed small sense organs, 

 often of much importance in classification. The mouth of 

 the medusoid is placed at the end of the clapper, and opens 

 into a cavity, which communicates with fine canals radiating 

 through the jelly of the bell. All these characters can, in 

 the case of some of the larger swimming-bells, be readily 

 made out, especially in living specimens, and on a calm 

 summer's day no difficulty should be experienced in obtain- 

 ing living medusoids. Even if a net be not at hand, it is 

 often possible to catch the little creatures from a boat in a 

 small bottle ; and there is, perhaps, no better way of study- 

 ing them than under such conditions, with the sunlight 

 playing on the water and the boat gently rocking beneath 

 the naturalist's feet. Then the delicate pulsating bells take 

 on a new beauty, and every movement displays some fresh 

 charm to delight the eye. It sometimes happens, on an 

 exceptionally calm day, that the surface 

 water simply swarms with medusoids of 

 many shapes and tints, varying in size from 

 tiny creatures, just discernible, as they float 

 along, to those with a diameter of about half 

 an inch. The size should be compared with 

 that of the large jelly-fish, which are not 

 very nearly related to the medusoids. 



As to the special characters of Sarsia, we 

 may notice that in the mature stage the manu- 

 brium, or clapper of the bell, is very long 

 and thick, extending downwards considerably 

 below the margin of the umbrella. This 

 character enables one to pick out the tongued 

 Sarsia, as it is often called, very easily from 

 other swimming-bells. It, together with the 

 other structural points described, can be 

 clearly made out from the figures. In this FlQ 15 _ Sargi t 

 tongue, or clapper, the eggs are developed, so swimming - beii, 

 that while in Conjne the eggs must fall near JK * 

 the parent colony, in Syncoryne, by the mucks. 



