1882 .] 
449 
[Kingsley. 
ment, until the formation of tadpole and the hatching of the 
embryo, takes jilace inside of the parent. In his species the first 
cleavage results in four blastomeres, in Molgula manhattensis 
that number is not reached until the second segmentation. The 
European forms do not develop a tail, but the processes develop 
while the embryo is still in the egg ; in our form a tail is devel- 
oped and the processes do not make their appearance until after 
hatching, and their number is not constant, sometimes reaching 
ten. I could not make out any fixed positions for some of 
them. In Lacaze Duthiers’ species the processes were five in 
number and four were found in the same horizontal plane. On 
the other hand the whole development seems, so far as w T e could 
learn from external observations, more nearly related to that of 
the normal forms and especially like that of Ascidia ampulloides 
as studied by P. J. Yan Beneden. The forms studied by Kupffer 
and Lacaze Duthiers seem to present an abbreviated and acceler- 
ated development, and possibly a critical study of the species 
studied by them and by myself will show that they are not so 
closely allied as their assignment to the same genus would 
indicate. 
Since this article was written I have seen Dr. Tellkampf’s 
paper on Molgula . 1 This gentleman claims that in Molgula we 
have an alternation of generations similar to that found in Salpa. 
That from the eggs of Molgula are directly developed the Mam- 
maria and that the Mammaria act as nurses, each individual pro- 
ducing a single tadpole which in turn goes through a development 
into Molgula. The Mammariae are described as being one line 
and one-half long, enveloped in a tough muscular mantle with a 
single terminal orifice which communicates with a branchial sac 
of the Ascidian type and which occupied three-fourths of the 
body cavity, while the heart and other organs occupy the 
remaining space. At this stage of development no intestine is 
fouiid. The embryo tadpole was situated at the end of the 
body opposite the external opening. These tadpoles finally 
break away from the nurses and the Mammaria continue their 
1 Notes on the Ascidea manhattensis, DeKay, and on the Mammaria manhattensis — 
Annals Lyc. Nat. Hist. N. Y., x, pp. 83-91, pi. m, 1871. 
PROCEEDINGS B. 8. N. H. VOL. XXI. 29 FEBRUARY, 1888. 
