59 



cinnamon-coloured, the lips sage-green and the tentacles ochre-yellow 

 whilst in the male the gonads, lips and tentacle-bulbs are of a dull 

 blue-gray colour. A somewhat similar phenomenon occurs in the An- 

 thomedusan Stomotoca dinema Agassiz 5 . 



Mr. Derzhavin does not mention the sex of the medusae collec- 

 ted by him, some information on this point would be of interest since 

 I was able to record the curious fact that all the individuals obtained 

 in Lake Qurun were of the male sex. 



The descriptions of the hydroid stages from the two localities do 

 not agree so perfectly as those of the medusae. Mr. Derzhavin des- 

 cribes the polyps as solitary, each springing from a small branched 

 hydrorhiza which is practically destitute of perisarc. The hydrorhiza 

 is similar in Mœrisia lyonsi but bears a variable although usually small 

 number of polyps. The hydranths from the Egyptian locality have the 

 tentacles arranged in a single more or less well-defined whorl around 

 the distal part of the body whilst in the Caspian Sea form additional 

 tentacles are to be found scattered over the whole hydranth. Mr. Derz- 

 havin does not describe any lateral buds such as occur on the proxi- 

 mal parts of the body in the Mœrisia lyonsi hydranths, it would be in- 

 teresting to know whether this type of asexual reproduction is confined 

 to the Lake Qurun form or whether it occurs in the Caspian hydroid 

 as well. 



Mr. Derzhavin discusses the systematic position of this Hydro- 

 medusan at some length and, whilst commenting on the difficulty in 

 assigning a place to the medusa among the Anthomedusan families as 

 they are constituted at present, concludes that the genus had best be 

 considered as a somewhat aberrant member of the Codonidae, in which 

 family I placed Mœrisia when I described it in 1908. 



The inclusion of this genus in the family Codonidae has not met 

 with universal approval, and Mœrisia certainly differs in some important 

 characters from the other genera which are grouped together in this 

 division of the Anthomedusae. Whilst agreeing with some of my critics 

 I must confess that I am still at a loss to find a suitable resting place 

 for this somewhat enigmatical Hydromedusan. 



In the structure of its gonads Mœrisia certainly bears a marked 

 resemblance to certain genera of the Margelidae and, in the light of 

 recent researches 6 , the continuous gonad and the hollow tentacle-bases 

 do not prevent its inclusion in that family. At the same time the struc- 

 ture of the tentacle-bulbs with ocelli on the outer or abaxial sides makes 



s A. G. Mayer, 1. c. p. 111. 

 6 C. Hartlaub, 1. c. p. 137. 



