58 



4. On Caspionema pallasi Derzhavin. the Medusa recently discovered in 



the Caspian Sea. 



By Charles L. B oui enger, M. A. 

 Lecturer on Zoology in the University of Birmingham. 



eingeg. 10. Mai 1912. 



In the current number of this journal (April 23., 1912) Mr. A. Derz- 

 havin publishes an interesting account of a Hydromedusan obtained 

 by him in the Caspian Sea near Astrachan and described as ( 'aspionema 

 •pattasi gen. et sp. nn. The excellent descriptions and figures of both 

 medusa and hydroid stages make it clear that this form is generically 

 and perhaps also specifically identical with the Hydromedusan which 

 Dr. Cunnington and I obtained in Lake Qurun during a collecting 

 expedition to the Fayoum Province of Lower Egypt a few years ago 

 and which was described by me in 1908 under the name of Mœrisia 

 lyonsi 1 . 



Mr. Derzhavin's figure of the medusa agrees in every respect with 

 the multitentacular form of the Egyptian medusa and it seems that all 

 of the 700 individuals collected by him in the Caspian Sea belong to 

 this variety; this is a point of some interest since of the Lake Qurun 

 examples only about 11 per cent possessed secondary as well as primary 

 tentacles the remainder being medusae with perradial tentacles only 2 . 



Dr. Hartlaub has recently called attention to a similar type of 

 variation in Podocoryne carnea* '; all the individuals from certain localities 

 bear four tentacles only, although the species is normally a multi- 

 tentacular one and in the typical form the medusae develop interradial 

 as well as perradial tentacles even before liberation from the parent 

 hydroid. 



The Egyptian and Caspian Sea jelly-fishes seem to differ in colour 

 only, Mr. Derzhavin describes his specimens as possessing pink gonads 

 and orange-brown manubria whilst the Lake Qurun medusae are prac- 

 tically colourless although brownish granules occur in the manubrial 

 endoderm and in the tentacle-bulbs of a few examples. 



This difference in colour may possibly be sexual, A. G. Mayer 

 in his monograph has described several cases of sexual dichromatic i. 

 for example in the female of Orehistoma pileus Lesson 4 the gonads are 



1 C. L. Boulenger, > On Mœrisia lyonsi, a new Hydromedusan from Lake 

 Quran«. Quart. Journ. Micr. Sci., London, Vol. 52, 1908, p. 357. 



2 C. L. Boulenger, »On Variation in the Medusa of Mœrisia lyonsi*. Proc. 

 Zool. Soc. London, 1911, p. 1045. 



3 C. H art la üb, Nordisches Plankton. XII. Craspedoten Medusen. I. Teil. 

 2. Lief.: Familie III, Margelidae. 1911. p. 218. 



4 A. G. Mayer, »Medusae of the World«, Carnegie Inst, of Washington, 

 Pubi. No. 109, 1910, Vol. 1, p. 211. 



