246 THE ANTARCTIC MANUAL. 
hardly proved to be the case. On the whole the inhabitants of the 
depths prove to be closely connected with fauna of the shallower 
waters. Still some interesting forms have been found. Ccphalodiscus 
dodecalophus, M‘Int., taken by the Challenger in the Straits of Magel- 
lan, has thrown some light on the more primitive members of the 
Chordate phylum. The existence of the stalked Crinoids, otherwise 
only known as fossils, of the deep-sea Meduse, to which Haeckel 
attributes an archaic structure, of the remarkable forms of deep-sea 
Holothuroids and Tunicates, go far to fulfil the hopes with which the 
voyage of the Challenger set forth. Whilst many deep-sea forms 
belong to the same families, and even to the same genera, as their 
shallow-water allies, and have probably descended to the depths in 
comparatively recent times, the existence of the large groups just 
mentioned, found as a rule in no other zones, shows that ages ago 
certain forms migrated to the abysses of the ocean. There, undis- 
turbed by the fret of tide or current, in quiet and gloom, they have 
developed into new forms, which are as characteristic of the depths of 
the great Ocean as a mountain-fauna is of the Alpine heights. 
SYSTEMATIC PART. 
PORIFERA. 
The first class of the Sponges, the CALCAREA, is unrepresented in 
the deep seas. None have been found at a greater depth than 
450 fathoms, and in our region the deepest were Amphoriscus 
elongatus, Pol., and Leuconia levis, Pol., at 150-310 fathoms, station 
145. The absence of the calcareous forms may be connected with 
the extreme difficulty of secreting lime which appears to obtain in 
the depths of the ocean, a difficulty which is shown by the thinness 
and tendency to disappear of the calcareous shell in molluscs and 
crustacea, of the test in echinoderms, and in the softness of the bones 
of deep-sea fishes, 
The Ksratosa, or Horny Sponges, are likewise not a deep-sea 
group, and are not found at a greater depth than 400 fathoms, except 
certain families described by Haeckel and not universally accepted. 
None of these are found in our district. 
The HEXACTINELLIDA found in the depths of the Antarctic region 
are as follows :—Belonging to the tamily Hopzscrezus, (1.) Holascus 
fibulatus, F.E.S., from stations 146 and 147, and outside the area 
