8 
THE VOYAGE OF H.M.S. CHALLENGER. 
body is visible which, I think, must necessarily represent the cement-gland. However, 
neither the place it occupies nor its structure shows any resemblance to the same glands — 
or what we must consider as such — in the Cypris of Lepas australis. Nor have these 
glands in the male of Scalpellum regium great conformity with those organs in the younger 
Cypris-stage of another species of Scalpellum ( Scalpellum triangular e) , which I figure in 
PI. II. fig. 4. In this stage the antennae (An) are still totally hidden within the valves, 
and the cement-glands (C. gl) form very large cellular masses situated on both sides of the 
thoracic part of the body between it and the valves. I think it is in this stage that the 
Cypris-1 arva leaves the mantle cavity of the mother. 
What we called the mantle in the Cypris of Lepas australis takes in the male Cypris 
of Scalpellum regium the form of a bag closed on all sides, with only a very small opening 
at the hinder extremity. This opening no doubt corresponds to the slit-like opening at 
the ventral side of the Cypris of Lepas. It also serves the same purpose. We see the 
very delicate and slender spines placed at the extremity of the legs come forth from this 
opening. For want of material I have not been able to study in detail the structure of 
the mantle, nor its musculature. I can only say that the mantle is composed of 
flat and pale rounded cells of O’Ol mm. in diameter, with a small clear nucleus, and that 
these cells are placed at a little distance from each other; that the muscular fibres form 
a single layer only, and are built up of elongate oval cells placed in longitudinal rows and 
each furnished with a distinct nucleus (PL I. fig. 7). Besides the body the interior of 
the mantle contains a mass of connective tissue with little grains and small fatty corpuscles 
scattered irregularly throughout its meshes. With regard to the body it is not difficult to 
observe the mouth (PI. II. fig. 3, M), the oesophagus (CE), and the stomach (St) ; the 
nervous system consisting of a supracesophageal ganglion (G S) and a single, rather large 
thoracic ganglion (G T) ; six pairs of very slender cirri with delicate spines at their 
extremities; a pair of long and well developed caudal appendages (C A). A dark 
coloured mass, consisting for the most part of yolk-fragments, makes up a great deal of the 
rest of the true body of the embryo Scalpellum. 
As for details, I can only say that the parts which surround the mouth are not very 
distinct, and that the very long oesophagus leads into a blind pouch of an oval shape, and 
that this pouch represents the stomach. The two branches of each cirrus are indistinctly 
divided into four segments ; the shape of each segment is cylindrical, with the exception of 
the last joint, which is conical, and slopes into the very long spines placed at the extremity. 
The first two pairs of cirri are somewhat different from the following pairs, inasmuch as in 
the first two the lower two segments are the only ones which are filled up with a mass of 
cellular structure ; so, when the cirri have shed the exuviae which now cover them, the 
cirri of the first two pairs undergo a considerable diminution in length. The very long 
caudal appendages in this stage are also represented only by the chitinous skin. After 
the last casting of skin they will no doubt have disappeared. 
