636 EDWARD T. BROWNE. 



Mr. Potts if he could spare a specimen for further examination. 

 A specimen was very kindly sent over from America b}^ Mr. 

 PottSj and I sincerely thank Professor Ray Lankester for his 

 generosity in handing it to me for examination. 



The figures of Medusa illustrating Mr. Potts' paper were 

 not drawn from a living Medusa, but from a specimen which 

 had been in weak formalin for several years. To obtain a 

 really satisfactory drawing of a Medusa it must be made whilst 

 the animal is alive. In drawing a preserved specimen allow- 

 ances have frequently to be made for contraction and dis- 

 tortion, and therein lies a source for error. After studying 

 living Medus£e for a few years the allowance for defects can 

 be fairly well estimated, though occasionally one may go 

 badly astray. 



The specimen which I examined was in formalin and in good 

 condition, but the umbrella was badly crumpled on one side. 

 It was a difficult object to examine owing to its minuteness, 

 being less than half a millimetre in diameter, and not easy to 

 fix in a definite position. The drawings which I have made 

 were finished before I received the proofs of Mr. Potts' plates. 

 I then noticed that my drawing of the Medusa did not quite 

 agree with that made by Dr. Moore, so I again examined the 

 specimen, but found that it was not necessary to make any 

 alterations. 



The Description op the Medusa op Microhydea (PI. 37, fig. 1). 



Umbrella. — The umbrella is campanulate, a little broader 

 than high (0*4 mm. in width and 0'3 mm. in height), with 

 thin walls. No nematocysts could be found on the ex- 

 umbrella, though the ectoderm cells were plainly visible. 

 The velum is broad, and here also the ectoderm cells with a 

 rounded nucleus could be easily seen. 



Stomach. — The stomach is large for the size of the 

 Medusa, being about three quarters the length of the cavity 

 of the umbrella. It appears to be more cylindrical than 

 quadrangular in transverse section, and tapers slightly 

 towards the mouth. In this specimen the mouth is fairly 



