On the Nutrition of the Salpa Embryo. 369 
confluent, and becoming deeper beyond the middle; beneath 
sparsely pubescent, somewhat densely, moderately coarsely 
punctured, the metasternum more finely punctured in the 
middle. 
Length 12, breadth 42 millim. 
Hab. N.E. Tasmania, Gould’s Country. 
I have seen three specimens of this species: two recently 
brought from Tasmania by Mr. J. J. Walker, late of H.M.S. 
‘Penguin,’ to whom they were given by Mr. A. Simson, of 
Launceston, from one of which the above description is taken 
(the other having been deposited by Mr. Walker in the British 
Museum), and a third in Mr, F. Bates’s collection. Mr. Bates’s 
specimen is lighter in colour, it being reddish brown, with 
the broad marginal stripe of the elytra stramineous. 
Sept. 23, 1893. 
LV.—On the Nutrition of the Salpa Embryo. 
By W. K. Brooxs*. 
AS the mammalian placenta nourishes and aerates the blood 
of the foetus by the diffusion of gases and food in solution 
through the walls of the blood-vessels, it has been generally 
taken for granted that the placenta of Salpa performs its 
function in the same way; and it has been described as 
divided into a foetal chamber and a maternal chamber, 
although its cavity is in reality part of the body-cavity of the 
chain-Salpa, and the blood which circulates in it that of the 
chain-Salpa. The Salpa embryo is bathed by the water 
which is constantly flowing past it, and it is therefore in very 
much closer relation to the external world than a mammalian 
embryo shut up in the interior of a large thick-walled body. 
There does not seem to be any need in Sa/pa for a respiratory 
placenta, and its thick spongy walls seem to indicate that it 
is not respiratory. We find in its structure nothing like the 
interlacing villi of the mammalian chorion, and the sections 
show that the embryo is nourished in a way quite unlike 
anything which has been described in the Mammalia. 
The subject is a very interesting one. The rapid growth 
of the Sal/pa embryo 1s one of its most conspicuous charac- 
teristics, and the nutrition which this rapid growth demands 
* From the ‘Johns Hopkins University Circulars,’ vol. xii. no. 106, 
pp- 97, 98. 
