50 THAUMANTIAS HEMISPH ARICA. 
It is very probable that, under the name of “ Medusa hemispherica,” the older and most 
of the more recent writers on Acalephe confounded many, or at least more than one, species 
of Thaumantias ; and, as very few of their notices extend to more than characters obvious at 
first glance, and common to a majority of members of the genus, it is difficult or impossible to 
ascertain what form or forms were meant when the name in question was cited. The figures 
given by Miller and Gronovius were evidently at such times borne in mind; but, as 
the importance of ascertaining the number and structure of the bulbous bases of the 
tentacula was not understood by any of the naturalists from whom I have given citations, 
unless Peron and Lesson be excepted, the reference to those figures cannot be received 
without suspicion. 
I feel sure that the animal I am about to describe and figure as Thaumantias 
hemispherica, is identical with that which was delineated by Miller in the Zoologia Danica, 
and clearly characterised by Peron, whose description, which [ here cite, applies to no other, and 
was probably drawn up after a study of Miiller’s account and figure, for the French naturalist 
gives no other locality than “ des cotes de Danemarck.” He characterises the species thus : 
“un ombrelle hémisphérique, déprimé 4 son centre; ovaires pédicellés et claviformes ; rebord 
entier, garni de trente-deux tentacules trés-courts et de trente-deux petites glandes ; ombrelle 
eris-bleuatre, parsemé de petits points plus gris; ovaires jaunitres, glandes marginales rouge ; 
1 centimetre.” The short diagnosis of Eschscholtz, “canalibus versus marginem disci 
clavatis,” founded on his misapprehension of the nature of the reproductive organs, would 
apply equally well to half the allied species here described, and his account of the number of 
marginal tentacles, “ihr Rand ist mit 16 bis 24 kurzen Fangfiden besetzt,” leaves us in no 
more certain position. The tentacles, however, as I have found by examination of very 
numerous specimens, do vary greatly in the several stages of the animal’s growth, though I 
have never seen them fewer than twenty. When full grown, the number is, as Peron has 
stated, thirty-six. This variation of number of tentacles with age is seen in several species of 
Thaumantias, especially in those with depressed umbrellas. Many species, however, present 
exactly the same number in their earliest and their oldest stages. Fortunately, the large 
conspicuous red or orange ocelli, and brightly coloured claviform reproductive glands, afford 
features combined with form, which will always enable us to recognise the true Zaumantias 
hemispherica without much difficulty. 
The individuals which I have examined in Zetland, where they abound in the bays and 
harbours, have a hemispheric, slightly depressed, transparent, smooth umbrella, sometimes 
measuring nearly three fourths of an inchacross. The margin in adult specimens usually 
bears thirty-two (sometimes more) tentacles, springing from as many large tubercle-like ocelli, 
which are vividly coloured with orange and red, and when magnified, are seen to present a 
small black dot. The formula for the ocelli and tentacles in the adult is probably 7x4-+-4. 
The tentacles are composed of granular tissue ; they are often carried short, not by contrac- 
tion, but by coiling up in a spiral. The sub-umbrella is moderately convex, and divided 
by the four gastric vessels, which pass in the lower half of their courses through four 
linear, claviform, purplish or yellowish ovaries, marked with purple or orange lmes. The 
stomach is short, rather broad, purplish, or tinged with pink, termimating in four lanceolate 
fimbriated lips. 
The abundance of individuals of this species in all stages of growth enabled me, when 
