72 



THE GEOLOGI&T. 



approach to yegetables, but which in their portions possessing the 

 power of sensation have the simplest animal organization — we find the 

 Astroeopora, with its slightly convex surface covered over with stellate 

 poreS; the former abode of the numerous-headed animal which con- 

 structed the strong fabric forming its habitation. Here, too, occurs 

 the Aulopora, with its chain-like form^ spreading itself over the sur- 

 faces of shells, and studded on its upper side with numerous aper- 

 tures from whence issued the heads of its occupant. The Michelina, 

 with its surface covered with depressed stars, arranged in an hexagonal 

 form like an antique pavement, here, too, makes its appearance in 

 considerable abundance; Stenopora. with its branching form and rugose 

 surface, here also occurs j and among them also we find Zaphrentis, 

 which, when broken perpendicularly, exhibits a structui-e like a series of 

 small funnels piled one upon another in its interior. 



Hook Head is, however, more famous for its Crinoids — those ancient 

 stem-like stone-lilies endowed with animal organization, and which 

 flourished in such gi'eat abundance in many of the paleozoic seas ; 

 numberless fragments of these forms occur, for the most part in the 

 state of fragments of stems ; sometimes in the form of the cup- 

 plates, and instances are not uncommon of almost perfect specimens 

 being found. 



One of the forms of crinoids, Adinocrinus, makes its appearance 

 generally in the condition of detached plates ; sometimes we have the 

 cup in a state of perfection showing the base composed of its three 

 pieces of quadrangular form, surmounted by numerous hexagonal 

 plates, and terminated by arms which branch in a dichotomous 

 manner. Cyathocrinus, too, occurs here, with its cup-base composed 

 of five pieces supporting five other larger plates, which form the 

 principal mass of the cup, and the base from whence the arms 

 emanated. Platycriiius also abounds, with its base composed of three 

 plates, surmounted by five larger pieces, which immediately support 

 the base from whence the dichotomous ones ai'ise. Foteriocj-inus, 

 with its five basal pieces, and its five subradial fi-agmeuts, and long 

 branching arms, here is met with. FJwdocrmus also is seen, with its 

 numerous plates beautifully fitted together, and looking, in some 

 species, like a rugose seed studded over with tubercles. It frequently 

 happens that here we meet with an individual crinoid in which the 



