CHARACTERISTIC DEEP-SEA TYPES. — POLYPS. 143 
the favorite abode of many kinds of ophiurans, and of sea- 
anemones, which are attached to the bare portions of the axis. 
We may mention among them a large species of Anthoptilum 
(Fig. 452), and a species of Balticina. (Fig. 453.) The extrem- 
ity of the axis of many of these wands is frequently laid bare 
by injuries. These naked spaces, as has been observed by Pro- 
fessor Verrill, are nearly always occupied by a peculiar Actinia 
(Actinauge), of which the sides of the flat base spread out 
longitudinally so as to wrap around the axis 
of the polyp and meet on the opposite side, 
forming a regular sheath by the coalescence 
of opposite edges. (Fig. 454.) The base of 
adjoining Actiniz coalesces in the same man- 
ner, and thus forms a continuous covering 
over the dead polyps. 
Professor Kölliker, who examined the 
* Challenger ” collection of Pennatule, came 
to the conclusion that the deeper portions of 
the Pacific and Atlantic oceans contain very 
few Pennatule at a certain distance from 
shore, and that these appear to have a wide 
distribution along the shores; the higher Fig. 454.—Actinange 
groups especially being characteristic of shal- ^ "exilis 4. (Verrill) 
lower water, while the simpler forms, the representatives per- 
haps of an. extinet fauna, inhabit the greater depths. 
The gorgonians are well represented in deep water by pecu- 
liar genera, of which the base is specially adapted for living in 
the mud, where it branches in all directions penetrating the soft 
ooze as if with roots ; all the shallow-water species having usu- 
ally a flat expansion of the base, by which they attach them- 
selves to solid substances, rocks, mollusks, ete. 
Many of these gorgo- 
nians are of an orange or 
»oddish orange color ; and 
the mast eharaet: istic of 
these is the elegant Das» 
gorgia Agassizii (Fig. 
1 (Veri) 455), a plumose much- 
Mo, 455 morria Agassizii 
Fig. 455, — Dasygorgia Agassizii. 1. 
