ON SHEPHEARDELLA, A NEW TYPE OF MARINE RHIZOPODA. 139 
it will doubtless become apparent in continued observa- 
tions. 
Histology » — Beyond what has been stated nothing has been 
elicited from living specimens concerning the structure of 
either integument, sarcode, or nucleus, but the examination 
of a series of mounted examples, some of which had been 
previously treated with reagents, has revealed some further 
interesting details in the two portions last named. 
As to the integument, further investigation only corrobo- 
rates the description already given, that it is a perfectly 
transparent, structureless, homogeneous membrane, flexible 
and elastic. Viewed in optical section with high powers, 
that is to say magnified from 600 to 1000 diameters, it 
appears to be double under some conditions of illumination ; 
but this is probably an optical illusion, caused by the unequal 
density of the surfaces, for when torn across it does not ex- 
hibit a double structure, nor is it separated into distinct 
layers by the action of reagents. Dilute acetic acid softens 
and swells it, and iodine stains it brown, but it is unaffected 
by carmine. 
Lying immediately within the integument, and closely 
adhering to it, is an exceedingly thin stratum of very finely 
granulated colourless protoplasm. Acetic acid causes this sub- 
cutaneous layer to rise into clear spherical masses destitute 
of granules but furnished with a large number of vacuoles. 
A camera tracing of it, mounted in glycerine jelly, magnified 
600 diameters, is given on PI. XYI, fig. 1. The sketch is 
taken from a specimen in which the denser sarcode occupy- 
ing the interior had retreated naturally from one end, 
leaving the integument with this delicate lining layer ex- 
posed. The nucleated granules and masses of firmer proto- 
plasm seen in the sketch are detached portions of the internal 
sarcode remaining upon it. 
The densely granular yellowish sarcode which occupies 
the whole interior of the body is affected in a very marked 
manner by osmic acid, dilute alcohol, and picro-carmine, 
the use of which was suggested to me by Professor Lankes- 
ter. By the application of these reagents each granule 
is rendered distinct and separate, and has the appearance of 
a nucleated cell, the central speck taking the carmine colour, 
whilst the peripheral portions remain yellow. The drawing 
(PI. XVI, fig. 2) is a camera tracing of a portion so treated, 
mounted in glycerine, and magnified 600 diameters. Some 
of the granules exhibit different stages of multiplication 
into two or more by fissiparous division, and their minute 
size will be realised by the figure referred to, 
