ZOOPHYTES. 



393 



icate organ of toucli. The terminal globe is filled with 

 proportionally large oval vesicles, each with a central 

 cavity, which are arranged in a divergent manner 

 around the centre, so that their tips shall reach the sur- 

 face of the globe ; these are those potent weapons of 

 offence called thread-cells {cnidm). The surface of the 

 globe is covered with short thick palpocils, which Dr. 

 T. S. Wright considers as prehensile organs. " These 

 palpocils arise, each as a 

 somewhat rigid process, 

 from the side of one of the 

 large thread-cells, buried 

 in the head of the tentacle ; 

 and they probably convey 

 an impression from bodies 

 coming into contact with 

 them, to the thread-cell, 

 causing the extrusion of 

 its duct." 



Besides these globe- 

 headed tentacles, there 

 are, on the lower part of 

 the club-foot, four other 

 organs similar in every 

 respect, except that they 

 are not furnished with 

 heads, nor any terminal dilatation whatever. They 

 project horizontally as the knobbed ones, but their ori- 

 gin, and the respective lines of their radiation, are in- 

 termediate or alternate ; in other words, if we consider 

 the globe-heads as pointing IST.-E. S. and W., the sim 

 pie ones point N.-E., S.-E., S.-W., and N.-W. 



From the carefully made observations of several 

 17* 



STAUEIDIA. 



