438 



THE VOYAUE OF H.M.S. CHALLENGE!*. 



Flu. 159. — Ctiulophaciw rfeijtn:*. u. 

 gen. et sp., a representative of the 

 Aseouematkla-. 



hitherto almost unknown, and in the present instance demanded special attention, those 

 specimens which had been hardened in absolute alcohol proved specially favourable ; also 



those portions which had been preserved in a relatively large 

 volume of spirit of the usual strength had to some extent 

 retained their original structure, better when voluminous or very 

 compact than when thin and loose in structure. 



" A serious drawback, however, arose from the fact that 

 the isolation of the different species had not always been found 

 possible. Even in the operation of dredging the different 

 sponges had undoubtedly come into violent contact with each 

 other ; in many instances fragments of one sponge remained 

 attached to the surface of another, or whole portions of one had 

 penetrated into the body of another. But in those cases in which several individuals had 

 been preserved in the same vessel it was afterwards found that the microscopic siliceous 



spicules, which are so important for diagnostic purposes, 

 had, in consequence of their lying loosely scattered in the soft 

 parts, become separated from one sponge and embedded in 

 another lying either beside or beneath it. Obviously such 

 intruding strangers, which may be only too easily mistaken for 

 natives, materially increase the difficulty of fixing the char- 

 acter of the species or the determination of a solitary portion, 

 especially when new and hitherto unknown forms are being 

 treated of, whose characteristic spicules must be determined 

 for the first time. It is true this danger of error is materially 

 diminished by comparative examination of the various portions 

 of the same sponge, or better still of several specimens of the 

 same species if they are to be had, but even then there remain 

 quite a sufficient number of instances in which a certain con- 

 clusion can be drawn only by the preparation of numerous fine sections, in which the 

 disposition of the spicules in question will decide whether they are really in their normal 

 situation. 



" The investigation began by a careful separation and arrangement of all the speci- 

 mens ; these were then placed according to the order of the; dredging stations, and then 

 one by one, thoroughly studied both with respect to their coarser as well as to their 

 microscopic structure. The numerous preparations, drawings, and notes which were 

 accumulated by this last difficult and tedious task form the foundation of the whole 

 work. It was desirable not only to establish the characters of the various species, but, 

 as far as possible, to discover the general plan of organisation of this curious and little 

 known group of animals. Oidy by the application of various oftentimes very complicated 



Flo. 160. —Hy(donemaelegans,n. sp.. 

 a representative of the Hyalone- 

 matidse. 



