480 MB. B. V. BEOWNE ON [Mar. 17, 



LEPTOMEDUS^. 

 Earn. ThattmantidjE. 



TlIAUMANTIAS lIEMISPlIyEBICA, Esclischoltz. 



The naturalists who studied marine life at the end oi' the last 

 century and at the beginning of the present one worked under 

 many dilliculties which have now passed away, mainly owing to 

 the improvements in lenses and in the advancement of the 

 chemical methods of preservation. 



The descriptions and figures of the jelly-fishes given by the 

 pioneers of marine zoology usually lack the details necessary at 

 the present day for the identification of the species. 



The marginal sense-organs or marginal vesicles, which require 

 the use of a microscope to show their presence and structure, have 

 been in most cases omitted, and now recent researches show that 

 they are very important organs for the identification of the species. 



The early workers on Medusa apparently did not recognize the 

 fact that Medusaj, like many other animals, pass through various 

 stages of growth and that the early stages are often unlike the 

 adult forms. 



This led to the early stages of Medusae being described as 

 distinct species, which together with the vague descriptions given 

 and inaccurate drawings has led to much confusion. 



I do not think that any good is to be obtained by retaining 

 inaccurate descriptions of Medusa;, and by burdening our litera- 

 ture, already overloaded, with long lists of useless synonyms. 



Medusa h.emispha'.rica was first described by Gronovius (1760) 

 from the coast of Belgium. Midler (1766) described a medusa, 

 as M. hemispheericci, from the coast of Denmark, and in a later 

 publication (1778) placed Gronovius's medusa as a synonym of it. 

 The desci-iptions and ligures given by these autliors are too vague 

 and inaccurate for the identification of the species. 



Peron and Lesueur (1809) separated the above medusa; into 

 two species — M. hemisphcei-ica, Gronovius, and Oceania danica 

 (Miiller). Fleming (1828) changed the generic name to Geryonia, 

 and Eschscholtz (1829) again changed it to Thaumantias and 

 united both species under the name of Thaumantias heinis/thairiva. 

 Lesson (1843) has copied from Eschscholtz, without adding any 

 fresh information. 



Macartney (1810) described two species of medusa) taken at 

 Heme Bay in 1 804. The one he called Medusa scintillans, which 

 is described and figured. This is clearly the common protozoon— 

 Noctilaca miliaris. Eor the other he suggested the name Medusa 

 lucida, but stated that it may be a variety of Medusa hemif:jphcerica, 

 Gronovius. It is not possible to identify Macartney's medusa 

 from his description. In the same paper Macartney described aud 

 figured a large Scyphomedusa under the name of Medusa pellucens. 

 This medusa was taken by Sir Joseph Banks. " On a passage 

 from Madeira to Eio de Janeiro the sea was observed by Sir Josepli 



