480 MR.E,T.BROWNE ON [Mar. 17, 
LEPTOMEDUS 2. 
Fam. THAUMANTID&. 
THAUMANTIAS HEMISPH HRICA, Eschscholtz. 
The naturalists who studied marine life at the end of the last 
century and at the beginning of the present one worked under 
many difficulties 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 Meduse apparently did not recognize the 
fact that Meduse, 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 Meduse being described as 
distinct species, which together with the vague descriptions given 
and inaccurate drawings has led to much contusion. 
I do not think that any good is to be obtained by retaining 
inaccurate descriptions of Meduse, and by burdening our litera- 
ture, already overloaded, with long lists of useless synonyms. 
Medusa hemispherica was first described by Gronovius (1760) 
from the coast of Belgium. Miiller (1766) described a medusa, 
as WM. hemispherica, from the coast of Denmark, and in a later 
_ publication (1778) placed Gronovius’s medusa as a synonym of it. 
The descriptions and figures given by these authors are too vague 
and inaccurate for the identification of the species. 
Péron and Lesueur (1809) separated the above meduse into 
two species—M. hemispherica, Gronovius, and Oceania danica 
(Miller). 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 hemispherica. 
Lesson (1843) has copied from Eschscholtz, without adding any 
fresh information. 
Macartney (1810) described two species of meduse taken at 
Herne Bay in 1804. The one he called Medusa scintillans, which 
is described and figured. This is clearly the common protozoon— 
Noctiluca miliaris. For the other he suggested the name Medusa 
lucida, but stated that it may be a variety of Medusa hemispherica, 
Gronovius. It is not possible to identify Macartney’s medusa 
from his description. 1n the same paper Macartney described and 
figured a large Scyphomedusa under the name of Medusa pellucens. 
This medusa was taken by Sir Joseph Banks. ‘On a passage 
from Madeira to Rio de Janeiro the sea was observed by Sir Joseph 
