—— 
THE ANNALS 
MAGAZINE OF NATURAL HISTORY. 
[FOURTH SERIES.] 
No. 35. NOVEMBER 1870, 
kaiaa 
XXXIV.—On the Larval State of Molgula; with Descrip- 
tions of several new Species of Simple Ascidians. By AL- 
BANY Hancock, F.L.S.* 
UNTIL quite recently it was generally considered that all the 
Ascidians, Simple, Social, and iie eg assumed in the larval 
condition the tadpole form. M. Lacaze-Duthiers, however, has 
lately shown that, in a certain species of the genus Molgula 
this peculiar larval condition does not exist, but, on the con- 
trary, the young, on issuing from the egg, is a comparatively 
inactive Amceba-like creature, in no way resembling the usual 
lively tadpole-like larva, either in form or mobility. From 
this discovery it might be inferred (and apparently M. Lacaze- 
Duthiers does infer) that all the members of the genus will 
present this exceptional feature. Such, however, is not the 
= 
In 1846, M. Van Beneden published his researches on the 
embryogeny &c. of the Simple Ascidiansf. This author 
described and figured at that time the tadpole larva of a Mol- 
gula, and, in fact, gave the whole history of the development 
of the species, which he considered new, and described under 
the name of Ascidia ampulloides. That this species is a true 
Molgula does not admit of a doubt; both the figures and de- 
scription prove this, although there are one or two slight dis- 
crepancies, which may perhaps be accounted for by inaccurate 
observation. The head of the tadpole-like larva is represented 
as rather long and inclined to ovate, with the anterior extre- 
