ZOANTHAPJA. 165 



circles. The extreme segments are dilated and variously cut, some- 

 times truncate, both sides being perforated with numerous pores just 

 visible to the naked eye, and arranged in rows ; the pores circular, 

 and level with the surface on the smooth and newly-formed parts ; but 

 in the older parts they form apertures of urceolate cells, which appear 

 to be formed over the primary layer of cells, giving to the surface 

 a roughish or angular appearance. The orifice is simple, contracted, 

 with a very small denticle on one side ; the thickness of the branches 

 varies from one half to two lines ; the interior is cellular ; the new 

 parts are formed of two layers of horizontal cells, but the older parts 

 are thickened by cells superimposed on the primary layers." 



Millepora moniliformis is a species which attaches itself to the 

 branches of the gorgons, and forms there a series of little rounded or 

 lateral lobes. The animal is unknown, the cells very small, unequal, 

 completely immersed, obsoletely radiate and scattered ; the polypier 

 fixed, cellular within, finely porous and reticulated externally, extend- 

 ing into a palmated form. 



Of tuberous or wrinkled madrepores, which consist almost entirely 

 of fossil species chiefly belonging to the Silurian formation, we shall 

 only note OyatkophyUwn as one of the best known species. 



There is no spectacle in Nature more extraordinary, or more worthy 

 of our admiration, than that now under consideration. These zoo- 

 phytes, whose history we are about to investigate wretched 

 beings gifted with a half-latent life only these animalcules so small 

 and so fragile labour silently and incessantly in the bosom of the 

 ocean, and, as they exist in innumerable aggregated masses, their cells 

 and solid axes finish by producing in the end enormous stony masses. 

 These calcareous deposits increase and multiply with such incalculable 

 rapidity, that they not only cover the submarine rocks as with a 

 carpet, but they finish by forming reefs, and even entire islands, 

 which rise above the surface of the ocean in a manner remarkable at 

 once for their form and the regularity with which they repeat 

 themselves. 



In noting the Indian and Pacific Oceans, navigators had long been 

 struck with the appearance of certain earthy bases, which presented 

 a conformation altogether singular. In 1601, Pyrard de Laval, speak- 

 ing of the Malouine (now the Falkland) Islands, said: "They are 



