12 JOHNS HOPKINS UNIVERSITY MORPHOLOGICAL MONOGRAPHS. 



Cutting the frenula caused the pedalia to contract but seemed 

 not to affect the ability to swim. Comparing the velarium of the 

 Cubomedusas with the velum of the Hydromedusas, I recall no 

 observations similar to the ones here noted, though it seems that the 

 two may have quite similar functions. It seems somewhat probable 

 that the velum, and also the velarium, may function in obtaining 

 food, and this besides their function in swimming. Their probable 

 function in swimming, as is well known, is evidently to narrow the 

 mouth of the bell and thus to cause the water to be forced out in a 

 smaller but more rapid stream, giving the animal a steady and more 

 prolonged movement through the water at every contraction of the 

 bell. In regard to taking food, I observed that a small crustacean, in 

 the process of being swallowed by an Olindiad, seemed to be held by 

 the velum being firmly contracted about it while the proboscis was 

 working itself over the crustacean. It would seem, furthermore, that 

 my supposition is supported for Charybdea by the fact that the 

 pedalia and tentacles were contracted so as to be brought inside the 

 bell when the velarium was cut. The stimulus of cutting the velarium 

 may be comparable to a stimulus from some object touching it, and 

 thus cause the pedalia and tentacles to come reflexly to aid in 

 capturing or holding the object, a fish, crustacean, or such, to be 

 captured. 



Pedalia, Interradial Ganglia, Tentacles Experiments 15, 23, 27-31, 

 41b. When the pedalia were removed, the power of the animal to guide 

 itself was completely gone. When one pedalium was cut the others 

 contracted, while stroking the outer edge of the pedalia, touching the 

 sensory clubs, or sharply pricking the subumbrella, often produced the 

 same result. (See also Nerve.) The upper part of the subumbrella 

 seemed not so sensitive and more seldom produced the reflex of the 

 pedalia, while the base of the stomach did not give it at all. Stroking 

 the outer edge of the pedalia of Tripedalia cystophora, the second of the 

 two species of Cubomedusse described by Conant, also caused the pedalia 

 to be contracted inwards. I may note here that the muscle fibers under 

 the ectoderm of the pedalia are specially well developed at and near the 

 inner and outer edges, both in Charybdea and Tripedalia. On the 

 flattened sides of the pedalia the muscle fibers are fewer. 



When the pedalia were cut off far enough up to remove the 

 interradial ganglia, coordination was not affected and the animal 



