8 
THE VOYAGE OF H.M.S. CHALLENGER. 
perisarc, even in the condition of the thin pellicle which occurs in Corymorpha , could be 
detected. 
I regard the elastic tissue of Monocaulus imperator as the homologue of the mesosarc, 
or supporting lamella, differing, however, from this layer as it shows itself in every other 
known instance by its massive development, its more decidedly fibrillated structure, and 
its great elasticity. 
I could find no trace of the papilliform processes which in Corymorpha, and in at 
least one species of Monocaulus , are developed near the base of the stem. In Mono- 
caulus imperator, however, the stem sent off from its proximal end a multitude of fine 
capillary tubes which, unlike the stem, were each invested by a very delicate chitinous 
pellicle, and were aggregated into a dense terminal plexus. 
The tentacles composing the proximal circlet as noted by Sir Wyville Thomson were 
in life about 4 inches long, almost transparent, and in most instances of a pale pink 
colour, while the mass of gonophores which lay just above their base was of a maroon 
colour. The colour of the stem in the recent animal was in most of the specimens a 
pale pink, becoming darker towards the base. 
The specimens when brought up were for the most part found to have the proximal 
extremity coated with mud, a fact which renders it pretty certain that in its natural 
attitude this gigantic Monocaulus lives with its proximal end plunged into the muddy 
sea bottom. 
With regard to the associates of Monocaulus imperator, the editor gives the following 
list from the same dredging. Actiniaria : — Paradis tubulifera, Liponema multiporum, 
Cereus spinosus, and Porponia robusta ; Asteroidea: — Porcellanaster tuberosus and 
Hyphalaster inermis ; Echinoidea : — Phormosoma tenue ; Ophiuroidea : — Ophioglypha 
orbiculata, Ophioglypha sculptilis, and Ophiomusium granosum; Holothurioidea : — Holo- 
thuria thomsoni; Brachiopoda : — Terebratula dalli and Piscina atlantica; Mollusca : — 
Malletia dunkeri, Glomus japonicus, Area ( Barbatia ) pteroessa, Pleurotoma sp., and 
Octopus januarii ; Fish : — Neobythites grandis, Macrurus asper, Macrurus altipinnis, 
Macrurus liocephalus, Gonostoma microdon, and Bathysaurus mollis ; in addition to 
Phoxichilidium mollissimum, Scalpellum vitreum, and a number of other Crustacea which 
perhaps may not have come from the bottom. All the above were new species, with the 
exception of the Piscina. 
CALYPTOBLASTEA. 
Family HALECIIDiE. 
Character of the Family. Trophosome. — Hydrothecse replaced by shallow saucer- 
shaped pedunculate appendages (hydrophores). Hydranths with conical hypostome. 
Gonosome. — Gonophores hedrioblastic. 
