348 Mr. J. W. Fewkes on a Method of 



other structures of Nanomia ar% identical with those of Agal- 

 mopsi's p/'ctu77i, a genus to which I formerly referred N^anomia, 

 tlie exceptional character of the cystous seems to me to 

 separate it from Sars's genus. 



The " oil-globule " forms a swelling at the proximal end 

 of the " cyston," and was not observed to be ruptured. There 

 seems, in point of fact, to be no opening through which it can 

 be discharged. Its regular form, its constancy, its position, all 

 stamp it as an organ of some kind. If we regard it as a float 

 of a new individual it differs very greatly from the adult float 

 of Nanomia. If we consider it a pigmented accumulation of 

 excretory matter we disregard completely its character as far 

 as the examination which has been made goes. It seems as 

 if it should be regarded as connected in some way or another 

 with the function of the cystous, but how I am unable at 

 present to say. 



lieviewing the data which have been brought forward, we 

 have the following facts bearing on the discharges of a coloured 

 fluid from organs of the body or the modification in colour 

 due to irritation in Si])hono})hores. 



1. Certain Agalmidaj, Forskalidte, and Apolemidaj dis- 

 charge a coloured fluid from their cystous. This fluid is 

 regarded as an excretion and is supposed by Ilajckel in one 

 case to be the means of protection, as the sepia of the Cepha- 

 lo])oda. 



2. A typical genus of Agalmidge {Agalma) has pigment- 

 glands on the bracts which discharge their contents when the 

 covering-scales are broken from the stem. This discharge 

 probably takes ]:)lace on simple irritation. 



3. Certain Hippopodidaj and a single known monogastric 

 Calycophore change colour somewhat on irritation (see Cliun's 

 description above). 



4. Nanomia has a prominent pigmented " oil-globule " at 

 the base of the cyston, which has never been seen to discharge 

 its contents. 



What conclusions may be drawn from the above state- 

 ments? Are we dealing herewith phenomena of a similar 

 character, or have we organs with two or three different func- 

 tions? Are these discharges when they occur simply the 

 throwing off of excretions, or do they also serve for protection 

 of the Medusa from its foes ? 



It seems not improbable that the physiological function of 

 certain of the tasters, which are known as cystous in Forshalia^ 

 is that of excretion. This power of throwing off excretions 

 may also serve for protection. Yet it must be borne in mind 

 that all the Calycophoridse, the Pneumatophoridse, and Hippo- 



