Ch. XXT.] fossils of the mountain limestone. 



515 



modern or Neozoic type, if, by the latter term, we designate (as pro- 

 posed by Prof. E. Forbes) all strata from the triassic to the most mod- 

 ern, inclusive. The accompanying diagrams (figs. 563, 564) may 



Fig. 563. 



Palaozoic type of lamelliferous cup-shaped Coral. Order Zoaxtilaeia bugosa, Milne Ed- 

 wards and Jules Hainie. 



a. Vertical section of Campophyllum flexuosum (Oya- 

 thophyllum, Goldfuss) ; £ nat. size : from the Devo- 

 nian of the Eitel. The lamella are seen around the 

 ioside of the cup; the walls consist of cellular tis- 

 sue; and large transverse plates, called tabula, di- 

 vide the interior into chambers. 



>. Arrangement of the lamella' in. Polycelia profunda. 

 Germar, sp. ; nat size: from the Magnesian Lime- 

 stone, Durham. This diagram shows the quadripar- 

 tite arrangement of the lamellae characteristic of 

 palteozoie corals, there being i principal and S inter- 

 mediate lamella?, the whole number in this type 

 being always a multiple of 4 



s. Stauria astraformis, Milne Edwards. Young group, 

 nat. size. Upper Silurian, Gothland. The lamella 

 in eaeh cup are divided by i prominent ridges into 4 

 groups. 



Fig. 5&i. 



Neozoic type of lamelliferous cup-shaped Coral. Order Zoaxthaeia apobosa, M Edwards 



and J. Haime. 



a. Parasmilia centralis, Mantell, sp. Vertical section, nat 

 size. Upper chalk, Gravesend. In this type the lamella 

 are massive, and extend to the axis of loose cellular tissue, 

 without any transverse plates like those in fig. 563 a. 



'?. Cyalhina Boicerbankii. Edwards and Haime. Transverse 

 section, enlarged. Gault, Folkestone. Lu this coral the 

 lamella are a multiple of six. The twelve principal plates 

 reach the central axis or columella, and between each pah- 

 there are three secondary plates, in all forty-eight. The 

 short intermediate plates which proceed from the columella 

 are not counted. They are called pali. 



?. Fungia patellaris, Lamk. Eecent : very young state. Dia- 

 gram oi its six principal and six intermediate septa, mag- 

 nified. The sextuple arrangement is always more manifest 

 in the young than in the adult state. 



illustrate these types ; and, although it may not always be easy for any 

 but a practised naturalist to recognize the points of structure here de- 

 scribed, everv o-eolooist should understand them, as the realitv of the 

 distinction is of no small theoretical interest. 



It will be seen that the more ancient corals have what is called* a 

 quadripartite arrangement of the stony plates or lamella — parts of 

 the skeleton which support the organs of reproduction. The number 

 of these lamellae in the palaeozoic type is 4, 8, 16, &c. ; while in the 

 newer type the number is always 6, 12, 24, or some other multiple 

 of six ; and this holds good, whether they be simple cup-like forms, 

 as in figs. 563 a and 564 a, or aggregate clusters of cups, as in 564 c. 



It is not enough, therefore, to say that the primary or more ancient 

 corals are genericallv and specifically dissimilar from the secondary, 

 tertiarv, and living corals, — for, more than this, all the most conspicu- 



