384 APPENDIX. 
the cenolithic period. The short, anthropolithic period is indi- 
cated by the linen o. (Compare vol. ii. p.14.) The height of the 
separate fields corresponds with the relative length of the periods 
indicated by them, as they may approximately be estimated from 
the relative thickness of the neptunic strata deposited between 
them. (Compare vol. ii. p. 22.) The archilithic and primordial 
period alone, during which the Laurentian, Cambrian, and Silurian 
strata were deposited, was probably considerably longer than the 
four subsequent periods taken together. (Compare vol. ii. pp. 10, 
20). In all probability the two tribes of worms and Zoophytes 
attained their full development during the mid-primordial period 
(in the Cambrian system) ; the star-fishes and molluses probably 
somewhat later (in the Silurian system); whereas the articulata 
and vertebrata are still increasing in variety and perfection. 
Prave VII. (Between pages 146 and 147, Vol. II.) 
Group of Animal-Trees (Zoophytes, or Cclenterata) in the 
Mediterranean. On the upper half of the plate is a swarm of 
swimming meduse and ctenophora; on the lower half a few 
bunches of corals and hydroid polyps adhering to the bottom 
of the sea. (Compare the system of Zoophytes, vol. ii. p. 182, 
and on the opposite page their pedigree.) Among the adher- 
‘ing Zoophytes at the bottom of the ocean there is, below on 
the right hand, a large coral-colony (1), which is closely akin 
to the red precious coral (Eucorallium), and like the latter 
belongs to the group of corals with eight rays (Octocoralla 
Gorgonida) ; the single individuals (or persons) of the branching 
stock have the form of a star with eight rays, consisting of eight 
tentacles, which surround the mouth. (Octocoralla, vol. 11. p. 143). 
Directly below and in front of it (quite below on the right), is a 
small bush of hydroid polyps (2), belonging to the group of bell- 
polyps, or Campanularie (vol. ii. p. 146). A larger stock of hydroid 
polyps (3), belonging to the group of tube-polyps, or Tubullariz, 
rises, to the left, on the opposite side, with its long thin branches. 
At its base is spread a stock of silicious sponges (Halichondria) 
