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to the margin than to the centre of the body. They are rather strong, and by means of a deep annular furrow are divided
into a fine terminal segment, and a considerably stouter basal part. The male genital papillae are prominent and situated as
usual. The hook-apparatus is of moderate size and development (Pl. VII, fig. 17). The chief hook (uncinus) resembles that
of M. cirriferum in shape, but the shank is a little more curved, and the fine extremity is still more bent. The supporting rod
(manubrium) is only a very little longer than the chief hook (Pl. VII, fig. 17). It is much bent, the stalk slender, and the
plate of the extremity is rather long and large; the terminal manual part is rather broad, and embraces the chief hook but
loosely. Of reserve hooks, I have found as many as 5, but usually 4. The segmental glandulous sacks with their circular,
relatively small, and little prominent openings, are situated between the parapodia level with their exterior margin. — The
mouth and anus are but little removed from the margin of the body, the latter less so than the former (Pl. I, fig. 2 mu & an).
The proboscis is well developed. The ventral nerve-cord is strikingly elongated, and has, thus, more resemblance to the usual
ventral cord in the annelids. The cerebral ganglia and oesophageal commissures are but little developed, whereas the tentacular
nerve-ring is considerably so. — Host. Antedon eel tica, Marenzeller. From station 343. Norwegian North-Atlantic
Expedition. Out ot the large number of this Comatula, obtained during the expedition, I have found not a few specimens (20—30)
ot this Myzostome. It is one of the more migratory species, as I have found specimens on the disk as well as on the
branches. Complemental males not found.
Myzostoma carpenteri, Graff (Pl. I, fig. 6, 7).
A little may be added to Graff ’s description of this species, if I may judge from the few specimens I have examined,
viz. 3, but, of which, only one was tolerably well preserved. The length of the largest of my specimens was 4.25 mm.
whilst the breadth was somewhat more. A complemental male, adherent to the dorsum of the largest specimen, measured
1.5 mm. in length. The body is thick and not quite circular in shape, being longer than it is broad. The intestinal branches are
extended nearly to the margin of the body, and there is only an extremely narrow, and but little translucent, margin which
is not continuous, being interrupted between the final pair of cirri, and here, the margin is thick, and the ventrum arched
towards the dorsal side. The narrow translucent margin is partly interrupted, and is slightly indented in front of the month.
The cirri are 20 in number, situated in two series, one on each side, with a small interval at the anterior extremity, between
the first pair, and a larger interval between the last pair of cirri. The dorsal surface is but little arcuated between the
anterior and posterior extremities, but is, on the contrary, considerably arcuated laterally. On the dorsal surface, there are
several distinct, slight, ridges (Pl. I, fig. 6, Pl. II, fig. 6 dr.), and 011 the ventral side, a very slightly prominent obtuse
longitudinal keel (Pl. II, fig. 6). The hooks are strong (Pl. VII, fig. 18). The chief hook has a strong and curved point. The
supporting rod is not long, probably somewhat shorter than the chief hook; it is relatively thick, not much curved, and has
a rather short terminal plate. The manual part of the hook is somewhat longer and not so broad as in the last mentioned
species, and it embraces the chief hook somewhat closer. Of reserve hooks, 3 were usually observed. The male genital
papillae are feebly developed, and are but little prominent; the}’ are situated on the exterior of the third pair of parapodia.
The little prominent apertures of the segmental glands are situated between the parapodia, nearer to the margin than them
(Pl. I, fig. 7, s., v.). On the exterior of each parapodium, and each gland, there is a depression, causing the margin, here, to
be thinner, and more translucent. The mouth is situated at a small distance from the anterior margin (Pl, I. fig. 7, mu.).
The cloacal aperture opens in a papilla situated just in the demarcation between the ventrum and dorsum Pl. I, fig. 6, an.;
Pl. II, fig. 8, an.). As the ventrum is, however, arched upwards towards the dorsal side, this species forms a transition
between species having the cloacal aperture 011 the ventrum, and those which have it on the dorsum. The colour white,
shading somewhat towards yellow. — Host. Antedon dentata, Say, (Ant. sarsii, Dub & Kor.). The few specimens found 3)
were all adherent to the disk, and the species belongs thus to the non-migratory ones. One complemental male was found
adherent to the dorsal surface of the largest hermaphrodite.
Integument.
The integument consists af 4 layers 1) cuticulum, 2) epidermis, 3) cutis, 4) integumental muscular layer; it is the
development of the two last named layers that, especially, varies in the different species, and appears usually to increase with
the thickness of the body. 1) The cuticulum is thin’) and apparently structureless. It, however, consists of two layers; one outer
pellucid, extremely thin, non-staining layer, and an inner thicker usually deep-staining one. The outer layer appears to be
feebly striated. The cuticle is, more or less, adherent to the subjacent epithelial cells from which it is secreted. I have
not detected any distinct openings or pores. 2) The epidermic cells vary, somewhat, in form and volume in the
’) In M. gigas its thickness is about 0.0035 mm.
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