L.M.B.C. MEDUSA. 389 



tentacles upon the margin of the umbrella, 4 single 

 perradial and 4 single interradial. Blackish tentacle-bulbs. 

 Hffickel's figure of Dijsmorphosa minima shows a con- 

 striction across the umbrella cavity. I do not think this 

 is a permanent constriction, but produced probably by 

 injury or death. In all medusae which have a permanent 

 constriction across the umbrella, the constriction is either 

 level with the top of the umbrella cavity or above it, so as 

 not to interfere with the size of cavity and the contractions 

 of umbrella. I have seen medusae under the influence of 

 cocaine die with a constriction across the middle of the 

 umbrella cavity. In the museum of the Marine Biological 

 Association at Plymouth I saw specimens of Dysmorphosa 

 minima, but labelled Bysmorphosa carnea. Nine of the 

 Plymouth specimens correspond to Haeckel's description 

 and five others only differ in the number of tentacles. 

 These show an increase in the perradial groups and ha\e 

 the tentacles arranged thus : — 



Perradial 2211 

 Interradial 1111 



2121 

 1111 



1112 

 1111 



2222 

 1111 



The perradial groups with two tentacles have one 

 tentacle longer than the other, the smaller one is evidently 

 growing. I took a single specimen at Port Erin, 1894, 

 of a medusa which is exactly like the specimens of 

 Dysmorphosa minima at Plymouth. It has four simple 

 oral tentacles ; eight single marginal tentacles ; and four 

 medusa-buds upon the manubrium. 



It is quite possible that Dysmorphosa minima is an 

 early stage of Lizzia hlondina. The Plymouth specimens 

 clearly show an increase of tentacles in the perradial 

 groups. 



Dysmorphosa minima may easily be distinguished from 

 Dysmorphosa carnea by the stomach being attached to a 

 short peduncle, and also by the presence of medusa-buds 

 upon the manubrium. 



