147 
On the Structure and Relationships of the Simple or 
Nucleated, and the Compound or Punctate Forms of 
Tiialassicollid.e. By John D. Macdonald, M.D.,F.R.S., 
Staff Surgeon, R.N. (With Plate XI.) 
Having perused Dr. Wallich's observations on the Thalas- 
sicollidae in the ‘ Annals and Magazine of Natural History’ 
for February, 18G9, I was induced to review my notes upon 
this subject, reaching as far back as 1852, the year just sub- 
sequent to that in which Professor Huxley’s excellent paper 
upon Thalassicolla was published ; and though I can do little 
more than follow in his footsteps, yet the little material col- 
lected by me, as well as the accompanying figures (which are 
all original), may be acceptable to the students of the Pro- 
tozoa. On the authority of Muller, one of the two forms of 
Thalassicolla punctata, described by Huxley with great 
accuracy, has received the name of Sphaerozoum, originally 
applied to something ambiguously described by Meyen, while 
the -other, or that with fenestrated capsules, has been named 
Collosphaera. It would seem, however, that Thalassicolla 
nucleata has escaped the criticism of the bibliographers, 
being retained as the nominal representative of the family. 
I shall at once proceed to the description of the figures, 
making such comments as may be suggested in passing. 
Sphcerozoum and Collosphaera. 
Fig. 1. A.n example of Sphserozoum, taken in the towing- 
net off the Cape of Good Hope, natural size. 
Fig. 2. Portion of the same, as seen with a quarter-inch 
power, but neither the central vacuolated portion, nor the ex- 
ternal common gelatinous envelope, is represented. The struc- 
ture of the puncta is simply as follows : — Beginning at the 
so-called nucleus, and proceeding outwards, we observe — first, 
(a) a bright yellowish, highly refracting, fatty globule; one, 
two, or more such globules being uniformly present in all the 
puncta of the same specimen, apparently in accordance with 
the stage of its development, and probably in some way con- 
nected with reproduction. • 
Secondly, (6), a mass of much smaller rounded, transparent, 
but not so highly refracting granules. 
Thirdly, (c), a distinct cell-membrane investing the fore- 
going parts. 
Fourthly, f d ), a plastic exudation upon the surface of the 
