1270 
THE VOYAGE OF H.M.S. CHALLENGER 
or ilreilges at the 25 stations whore the recorded depths were greater than 2500 fathoms, 
are enumerated in zoological sequence from the Sponges to the Fishes. Those animals 
which were taken in this deepest zone and not anywhere else outside of it during the 
Expedition are indicated by an asterisk. This list is followed by subsidiary lists in small 
type, viz.: — First, a list of those species taken at more than one Station within the zone 
deeper than 2500 fathoms ; second, a list of those species taken in the zone below 2500 
fathoms as well as in the next shallower zone between 2000 and 2500 fathoms, and 
similar lists for those species common to this deepest zone (deeper than 2500 fathoms) 
and the still shallower succeeding zones up to the shallowest ; third, a list showing the 
new genera taken only in the zone deeper than 2500 fathoms, and the number of species 
beloncriii" to each of these genera. 
Tlie species procured by the dredge and trawl in the zone between 2000 and 2500 
fathoms arc treated in an exactly similar manner, and so on with each succeeding 
shallower zone, but in the subsidiary lists it is unnecessary to repeat the lists of species 
common to the zone under consideration and the deeper zones, as these species appear 
already in the lists of animals from the deeper zones, and the pages are merely referred to. 
In order to avoid the repetition of the names, and to save the large amount of space 
necessarily involved in publishing similar lists to show the geographical distribution of 
the animals procured by the dredge and trawl during the Challenger Expedition, the 
bath}Tnetrical lists have been made subservient to that purpose by adopting the expedient 
of using the letters S, T, and N, to denote the distribution in tropical and extra-tropical 
areas: — S placed after the name of a species indicates that it was taken south of the tropic 
of Capricorn ; T placed after the name of a species indicates that it was taken within the 
tropics of Capricorn and Cancer ; N placed after the name of a species indicates that it 
was taken north of the tropic of Cancer. These letters represent the geographical distri- 
bution of the species irrespective of depth, and they simply point out the area or areas in 
which the species was obtained by the Challenger. It must be borne in mind that all the 
information in these distributional lists refers only to the collections of the Challenger 
Expedition. Thus, if a previou.sly-described species occur in the lists with an asterisk, it 
nmst not be presumed that the species has never been observed except in that zone of 
ilepth, but merely that the Challenger obtained the species only in that zone. Again, if 
a previously-described species apj)ear with the letters S and T, it must not be supposed 
that the sj)ccies has never been observed north of the northern tropic, but merely that 
the Challenger olRained the species only to the south of the northern tropic. If, for 
in.stance, a sjMScies with an asterisk has only S after it, then it was obtained by the 
Challenger in that zone only, and south of the southern tropic. In considering the 
|KTCcntages given in the following notes, it must be remembered that a certain number of 
n|»feic8 found in more than one zone arc therefore counted twice or oftener. 
