76 Dr. H. Fol on the Family Tintinnodea. 
In Tintinnus ampulla this thickness is O'S. The space 
which separates these two lamine is a little thinner than the 
laming themselves, and is divided by a number of little secon- 
dary partitions which pass from one lamina to the other. The 
arrangement of these lamelle varies according to the species 
and produces the design which characterizes the test of each 
species. At the free margin of the test the two lamine unite 
by bending round and form only one. 
In the genus Cyttarocylis the general arrangement is the 
same, but the lamine are more separated and the partitions 
less numerous and stronger, leaving more apparent alveolar 
spaces (Pl. IV. fig. 10). 
Dictyocysta, besides these alveoli, presents perforations of 
the whole wall. 
Lastly, in Condocylis, which I now think may be united 
with the genus Codonella, the wall is simple, of variable and 
irregular thickness, and inerusted with foreign bodies. 
Hence there are no profound differences except between the 
agelutinant tests with massive walls and the tests with double 
walls united by little septa. The latter only differ among 
themselves by the number and arrangement of the septa; the 
fundamental structure remains the same. I previously (XII. 
pp- 18, 22 [ 245, 248]) described the alveolate tests as formed of 
a sort of trellis, closed only on one side by a continuous mem- 
brane. ‘This statement must be corrected in this respect, that 
the alveoli are found in all parts and enclosed between two 
continuous membranes. 
The animals preserved by the method indicated show clearly 
various details of structure which escaped me in the animals 
treated by the usaul methods. In gallic acid the nucleus 
acquires a dark brown tint, which enables it to be distin- 
guished at the first glance. In Tintinnus ampulla and T. 
spiralis, the only two species of the genus that I have met 
with this time, I have never seen more than a single nucleus, 
which was of considerable size, and placed either near the 
middle of the body or further back and towards the peduncle. 
In my preparations I have also met with many individuals 
in which | could discover no element of this kind; it isso easy 
to see when it exists that I incline to believe that in certain 
phases of existence it is really absent or profoundly modified. 
In Zintinnus ampulla the nucleus is oval, and measures as 
much as 50 w inits greatest diameter (see Pl. IV. fig. 7). It 
is formed by a thick superficial layer, which remains homo- 
geneous in the reagents employed (perchloride of iron, alcohol, 
and gallic acid), and acquires a uniform brown tint. I have 
been unable to detect any distinct membrane at its surface. 
= es WTR eee 
