X 
THE VOYAGE OF H.M.S. CHALLENGER. 
Tubes. 
The majority of the tubes formed by the Annelids collected by the Challenger have 
been described along with their inhabitants, but a few remarks are necessary on certain 
empty tubes. A very striking form is one procured by the trawl at Station 298 (south 
of Valparaiso); lat. 34° 1' S., long. 73° 56' W.; depth, 2225 fathoms; bottom tem- 
perature 35°‘6, surface temperature 59° ; sea-bottom, blue mud. The same form comes 
from the neighbouring Station 299. It consists of a triangular tapering tube (PI. XLIX. 
figs. 8, 9) composed of very fine dark mud, and having the three ridges hispid vdth short 
muddy processes. On magnifying the surface between the ridges (fig. 9) peculiar trans- 
verse markings, which almost resemble scutes, are observed. Its occupant probably 
pertained to the Terebellidse or a neighbouring family, but no trace of it was found. 
The tubes composed of the secretion produced by the body of the animal, such as 
those of Hyalincecia and Eunice, are of course independent of their surroundings, but the 
majority have a composite nature, viz., have either an internal lining of the secretion or 
an admixture, and an external investment of mud or other solid particles. On the blue 
mud and red clay the tubes are often almost entirely formed of these deposits. As 
GlohigerincB appear these are studded over the surface of the mud ; while in certain 
localities the discoid Foraminifera are set on edge on the surface of the mud so as to 
render the tube hispid. Massive tubes, almost entirely composed of Foraminifera, 
occurred at Station 158 (south of Australia). Small bivalves and other Mollusks are also 
largely used to strengthen and protect muddy tubes, and the extreme development of 
this method is shown in the empty tube in fig. 13 of PI. XXXIXa. from Port Jackson. 
The tube is quite squamous, from a close series of Molluscan valves which overlap each 
other around the tube. 
General Kemarks. 
The drawings of the first fifty-five plates were made by my niece, who patiently 
endeavoured to render them as life-like as possible, though it was hardly possible 
in all cases to represent minute structural detail. Moreover, many of the specimens 
were so much injured that difficulty was felt in making a satisfactory picture ; indeed, 
previous knowledge of their structure was necessary in this respect. Upwards of thirty 
plates and the woodcuts are from my own drawings, a fact which will explain the 
somewhat tardy a^Dpearance of the Report, which had to be carried on amidst one or two 
distractions. Mr. Edward Prince and Mr. John Wilson, my former students and prize- 
men, aided me with several of the concluding plates ; while Dr. R. Marcus Gunn, 
previously associated with me in Perthshire, and now one of the ophthalmic surgeons at 
Moorfields, illustrated his own observations on the eyes of the Alciopidse and Phyllodocidse. 
