28 
THE YOYAGE OF H.M.S. CHALLENGER. 
indeed be regarded as such. Krohn has not given a description of these glands, nor is 
such a description to be found in the literature of the group. For Balanus I myself 
published figures of these glands some years ago, 1 when it was my opinion that the 
ovarian coeca might perhaps develop from these bodies — a serious error pointed out by 
Claus. My excuse was firstly that these bodies, scattered everywhere between the 
young ovarian cceca, had never been observed in a sessile Cirriped before, and secondly 
that Darwin had led me into error by describing the cement-glands as adhering to the 
basal membrane or basal calcareous plate of the Balaninse. I should have paid more 
attention to a footnote in Krohn’s paper (p. 357), in which he states his opinion that 
the true cement-glands of the Balanidse might also be found between the ovaries or in the 
connective tissue surrounding the mantle. 
The cement-glands of Lepas anatifera, of Conchoderma virgatum, and of Scalpellum 
vulgare are nearly of the same shape and size. Those of Lepas anatifera are a little larger, 
the longest diameter measuring 0T5 to 0'2 mm., whereas those of Scalpellum vulgare are 
smaller, having a diameter of about 0T25 mm. (The largest diameter of one of the 
cement-glands of Balanus improvisus is not quite 0'2 mm.). The interior of the cells 
is filled with a plasmatic mass, which shows the curious property of staining rather 
intensely with aluminium carminate. At the same time, the large nucleus, which 
occupies nearly the centre of the cell, and which measures half the length of the cell 
itself, is coloured also and much more intensely. In many preparations the body of 
the cell shows an extremely delicate granular structure, whereas the nuclei are coarsely 
granulated, or appear to have a fibrillar structure. In Lepas nucleoli have not 
yet been observed. PI. II. fig. 5 shows the condition of the cement-cells in the 
Cypris-larva. I do not quite understand in what way the pear-shaped gland 
develops from these cells. The size of the latter is about 0‘03 mm., at least in the 
case of Lepas australis. Towards one side, and as a rule in the longer axis of the 
cell, its wall is produced so that the cell assumes the shape of a pear ; this produced part 
slopes into a long and narrow duct (PI. V. fig. 5). The structure of this duct is very 
simple ; here and there small cells are visible in its wall (measuring about 0'005 mm.), 
which on the exterior is lined by a kind of thin cuticle. 
The ducts of the different cement-glands unite together to form a much more 
capacious duct ; a little before the place where the junction is observed, a transverse 
short duct often runs from one branch to the other; all the ducts together form an 
irregular network, the thickest branches finally pour out their contents into two 
longitudinal ducts. The ducts (fig. 5, d), which communicate directly with the glands, 
have a diameter of about CP025 mm. ; the two longitudinal ducts in which the 
contents of the narrow ducts are evacuated, measure about 0‘05 mm. in width. In a 
1 P. P. C. Hoek, Zur Entwickelungsgeseliichte tier Entomostraken, I. Embryologie von Balanus, Niederlund 
Archiv f. ZooL, Bd. iii. pp. 47-82, 1876. 
