MEDUSA. 57 



getetiiious parts lemaiu. The hasal portion of the arm, dose to the mouth, is very 

 much compressed laterally, resembling a thick Heshy leaf, ul)out 130 mm. liroad aud 

 about 20 mm. thick. 



The lower wall of the stomach is thick and strong for carrying the weight of 

 the oral arms. In it there are four interradial genital openings, wliich are semi- 

 oval in shape, mea.suring about 20 mm. in length. These openings are very small 

 for the size of the stomach, but larger openings would tend to weaken its lower 

 wall. From one of the openings a gonad is protruding about 50 mm. Tlie 

 stomach is circular in shape, forming a large cavity without internal septa and without 

 distal pouches. From the periphery of the stomach go forth many radial canals. 

 The courses of several of the canals were traced by dissection. They pass through 

 tlie layer of jelly and come to the surface of the sub-umbrella. It has already been 

 stated that the Medusa is of a dark reddish-brown colour, wliich is an opaque surface 

 layer confined to a very thin skin, which can be peeled off from the underlying jelly 

 This skin, at first, was mistaken for the ectoderm, but after further investigation and 

 consideration, it seems more likely to be an artificial product, formed after preservation 

 On tracing the radial canals from the stomach it was found that they came to the 

 surface of the sub-umbrella near the periphery of the stomach, and that their open 

 ends were covered by the reddish skin. There is not the slightest trace of a canal 

 .system over the surface of the sub-umbrella, nor of any muscles. One would naturally 

 expect to see powerful circular muscles on the sub-umbrella, con.sidering the size of 

 and thickness of the umbrella, and the great length of the oral arms. I believe that 

 all the circular muscles, and the whole of the canal system on the sub-umbrella, have 

 peeled off. Their absence would account for the abrupt termination of the radial 

 canals after passing through the wall of the stomach. 



The margin of the umbrella is very much damaged and broken, but there are 

 indications, here and there, of lobes, which are, perhaps, the basal portions of larger 

 lobes. There is not the slightest trace of a tentacle, nor of a sense organ. Except 

 for the gonads the specimen is but little more than a gelatinous skeleton. 



The presence of a central mouth, and oral arms without internal canals excludes 

 this ^Medusa from the Rhizostomata. It, no doubt, belongs to the Semaeostoniata. 

 The absence of marginal gastric pouches, and the presence of radial canals, indicate 

 that it belongs to the Ulniarida3. It is best to place this large Medusa provisionally 

 in the genus Dipluhnaiis, as it is too imperfect to justify the pos.session of a new 

 ceneric name. 



