404 On the Anatomy and Embryology of the Phalangiide. 
spinning-glands of Perdpatus and the sete-forming glands of 
the Annelids proves to be untenable. 
10. The cephalothoracic glands described by Krohn are 
constituted in the final stages of development as two pyriform 
invaginations of the ectoderm at the side of the two eyes 
(figs. 40, 41, and 47, ¢.dr.). In the ectoderm cells of the 
glands there commences at an early period the secretion and 
accumulation of a dark pigment which forms two black 
spots upon the surface of the embryo, which is still perfectly 
white; these spots are visible like the eyes through the egg- 
membranes. Simultaneously with the glandular structures 
which have been described there exists in the embryo a pair 
of provisional organs of a glandular character. In Cerastoma 
cornutum these appear as two groups of large cells, lying 
one on each side in the cephalothorax near the eyes. Hxter- 
nally these cells are directly covered by the ectoderm, and 
they appear to be separated from the body-cavity by a thin 
membrana propria. In addition to a large nucleus the cells 
of this organ enclose peculiar concretions, which take a deep 
stain from carmine. Although covered by the ectoderm these 
cells nevertheless possess a communication with the outer 
world by means of a special aperture, through which the 
concretions which are formed in them are conveyed to the 
exterior. In the sections a compact mass of these excretions 
generally lies at this aperture (figs. 89, 40, 41, 44, and 45). 
In another undetermined species of Phalangium the glandular 
structure of this organ was even more pronounced. In this 
case it consisted of a tolerably large hemispherical complex 
of cells, which projected freely into the body-cavity and was 
attached to the ectoderm by a relatively smaller portion 
(figs. 42, 43, 46, and 47); the apices of the columnar and 
distinctly defined pyramidal cells of this organ met together 
in a point, while their broad bases formed a hemispherical 
surface. In each cell a large nucleus was situated not far 
from the base, while the excretory products were accumulated 
nearer the apex. ‘The external aperture of the gland had the 
form of a small pit, filled with secretion deeply stained by 
carmine; short rods of this secretion radiated from this pit 
between the apices of the cells (fig. 43). But these glands 
had not exactly the same structure in all preparations of this 
species of Phalangium; in some cases they were suggestive 
of those of Cerastoma cornutum (fig. 48). At the same time 
the embryos investigated were all at the same stage of deve- 
lopment. I have consequently found in two species of Phalan- 
gium during embryonic development a peculiar glandular 
organ, which lies in a single pair in the cephalothorax, 
