CRIBRILINA RADIATA. 185 



depends on the primary composition of the cell-wall^ and 

 indicates the course of its development. The ridges radi- 

 ating towards the centre represent the rib-like processes 

 given off from the margin of the young cell^ as in the 

 genus Membraniporella, which ultimately meet and form 

 a protective covering. These ridges are united laterally 

 by outgrowths of stony matter occurring at intervals ; 

 and the spaces between the connecting links are repre- 

 sented by the interstitial punctures of the adult organism. 

 So that the genus is founded not on any trivial peculia- 

 ritiesj but on the essential structure of the cell itself. 



Cribrilina marks a transitional stage in advance of that 

 represented by Membraniporella. 



A considerable number of fossil species are known, 

 some of which reach back to the Cretaceous deposits. 



Cribrilina radiata^ Moll. 

 Plate XXV. figs. 1-9. 



EsciiARA KADiATA, MoU, Scerincle, 63, pi. iv. fig. 17. 



Lepralia innominata, Couch, Corn. Faun. iii. 114, pi. xxii. fig. 4 (worth- 

 less) : Johnston, Br. Z. ed. 2, 319, pi. Iv. fig. 12 : Busk, 

 B.M, Cat. ii. 79, pi. ksxvi. figs. 2, 3: id. Crag Pol. 40, 

 pi. iv. fig. 2: Hincks, Devon and Corn. Cat., Ann. N. H. 

 ser. 3, ix. 203 (p. 43 sep.) : Manzoni, Siippl. Bryoz. Medit. 

 prima Contr. 4, pi. i. fig. 5 (Sitzb. k. Akad. d. Wissensch. 

 Ed. Ixiii. 1. Abth. Feb. -Heft, 1871) ; Bryoz. Pliocen. Ital. 

 prima Contr. 8, pi. ii. fig. 13 (Crag form). 



? Flustra Pouilletii, Aicdouin, Savigny, Egypte, pi. ix. fig. 12. 



? Lepralia multieadiata, Ecuss, Oberburg, 31, pi. x. fig. 5; Palaoutol. 

 Studien, ii. 43. 



Lepralia scripta, Beuss, Sitzungsb. k. Akad. d. Wissensch. Bd. 1. 28, pi. xv. 

 fig. 3 ; Bryoz. d. deutsch. Septarienth. 1866, 58 ; (Cellepora), 

 Polyp, d. Wiener Beckens, 82, pi. ix. fig. 28 : Mansonl, 

 Suppl. &c. 5, pi. i. fig. 6. 



Lepralia pretiosa, Ecuss, Bryoz. d. deutsch. Septarienth, 59, pi. viii. 

 fig. 4. 



Lepralia calomorpha, Ecuss, L c. 62, pi. xi. fig. 10. 



