SECTION OF NAKED EYED MEDUSA. 123 



brium of Tiaropsis indicans should, in the absence 

 of more definite information, refer a distant seat 

 of injury to that tract of collected afferent elements 

 through which it actually receives the strongest 

 stimulation. 



Staurophoi'a Laciniata. 



Tliis is a Medusa about the size of a small saucer 

 which responds to stimulation of its marginal 

 ganglia, or radial nerve-trunks, by a peculiar 

 spasmodic movement. This consists in a sudden 

 and violent contraction of the entire muscle-sheet, 

 the effect of which is to draw together all the 

 gelatinous walls of the nectocalyx in a far more 

 powerful manner than occurs during ordinary swim- 

 ming. In consequence of this spasmodic action 

 being so strong, the nectocalyx undergoes a change 

 in form of a very marked and distinctive character. 

 The corners of the four radial tubes, being occupied 

 by comparatively resisting tissue, are not so much 

 affected by the spasm as are other parts of the bell ; 

 and they therefore constitute a sort of framework 

 upon which the rest of the bell contracts, the 

 whole bell thus assuming the form of an almost 

 perfect square, with each side presenting a slight 

 concavity inwards. These spasmodic movements, 

 however, are quite unmistakable when they occur 

 even in a very minute portion of detached tissue ; for, 

 however large or small the portion may be, when 

 in a spasm it folds upon itself with the characteris- 

 tically strong and persistent contraction. I say 



