HARKNESS — THE GEOLOGY OF UOOK POINT. 
73 
stem, cup, arms, and thin uet-like membranes retain all their original 
perfection, and they appear as if they had been suddenly enveloped 
in some rapid deposition of mud, while they were resting from their 
labours and digesting the food which their membraneous extremities 
had caught. In some instances the stems are in such a condition as 
to allow us to judge of the arrangement of the joints composing 
them, as also of their flexibility. The surfaces of some of the strata 
are covered by these stems, and sometimes the stems have such a 
sinuous and convoluted aspect as to lead to the conclusion 
that these crinoids covering the bottom of the carboniferous 
sea, moved about under every influence of wave and current, as 
trees do on land when a breeze is powerful enough to shake them. 
Hook Point is equally celebrated for the remains of that tribe 
of animals which is known under the name of Bryozoa, and 
which in their internal structure have great affinity to animals 
constructing and inhabiting bivalve-shells. Among these we have 
Diastopora, a parasite, which lived and built its habitation on other 
Bryozoa, forming a small patch of calcareous matter, having cells with 
semicircular apertures pointing outwards. Glauconome — one form of 
which presents a feather-like aspect, having a central shaft, from 
whence issue numerous obliquely placed bars, running together 
regularly, and leaving interspaces of an oval form, the bars having 
on one side a row of pores along each margin — is seen in considerable 
profusion. Polypora, a net-like form, having its under surface devoid 
of pores, but with the upper sui'face covered with several rows of cells 
on each of the upright bars, also appears at Hook Point. The form 
of Bryozoa which occurs in the greatest profusion and perfection is 
Fenestella. Several distinct species hei-e make their appearance, and 
in some cases the limestones appear to be almost altogether made up 
of this form. It has a window-like aspect when magnified ; but, seen 
without the aid of the microscope, has somewhat of a net-like 
structure ; its under surface, like the Bryozoa generally, is devoid of 
pores ; but the thicker upright bars have commonly a finely striated 
sxu-face. The upper side of the bars is usually marked by a central, 
well-exhibited keel, and on the outer side of this are the numerous 
pores from whence the heads of the animal inhabiting the Fenestella 
issued. The thin cross-bars which serve to connect the thicker pore- 
