F. D. Longe — Oolitic Tolyzoa. 25 



of classification is sonnd, the Oolitic Escliaroids themselves must be 

 divided between two different orders. If, on the other hand, their 

 study proves generic affinity between the whole group, we must 

 look in another direction for an escape from the dilemma. 



The weight of the evidence which these forms present of being 

 closely allied, either as different species of the same genus, or as 

 mere varieties of the same species, can only be fully appreciated by 

 an examination of the forms themselves ; but it is sufficient evidence 

 of such affinity that Jules Haime, the only student of these forms 

 that I am aware of, who has written a systematic account of them, 

 ■was so convinced of their generic identity that, notwithstanding 

 D'Orbigny and Michelin having expressed diff'erent views as to many 

 of them, he classed them all as Tubilipora,^ a division corresponding 

 to the Cyclostomata of later authors ; and he did this in face of the 

 objection, that, according to such a view, the Cheilostomata (or, as 

 he called them, the Escharidce), which were so abundantly repre- 

 sented in the Chalk, must have originated, not by any modification 

 of corresponding Oolitic forms, but either by a new creation, or by 

 a process of development from some obscure form, which took such a 

 rapid and remarkable course as to produce in the very next period 

 a number of Escharoid forms so similar in their character and even 

 cell feature as to be undistinguishable from the Oolitic Escliaroids 

 by such observers as D'Orbigny and Michelin. 



A reference to the points of doubt or dispute raised by these 

 authorities, in their attempts to apply this system of division to these 

 Escharoid forms as are represented in the Oolites and the Chalk, will 

 show at once the gist of the question raised. D'Orbigny figures 

 and describes a Cretaceous form very similar to some of the Oolitic 

 species, first as an Eschara, in his order Cellulines ; and afterwards 

 as an Elea, in his order Centrifugines. He did not, however, make 

 this change in the classification of this form until he had introduced 

 into his system a sub-order which he called the Centrifugines 

 Operculines, i.e. forms which combined the tubular cell of the Cyclo- 

 stomata with the operculum of the Cheilostomata. To this sub-order 

 he assigns two families. 1. The Eleid89, embracing several of the 

 ambiguous Escharoid forms common to the Oolites and the C/halk — 

 and a dendroid form, Melicertites, also common to these two groups. 

 2. The Myriozoumidse, in which he placed the genus Myriozoum — a 

 living genus the ambiguous character of which is recognized by recent 

 authorities.^ In his account of the Oolitic Polyzoa, Jules Haime, in 

 dealing with one of the forms classed by D'Orbigny as an Elea, refers 

 to D'Orbigny's view as to its possessing opercula, but rejects it at 

 once as a mere error of observation, suggesting that what D'Orbigny 

 took for opercula was merely a disfigurement of the cells in a badly- 

 preserved specimen. As, however, the lids or closures which 

 D'Orbigny determined to be opercula are very evident in the best- 



' Memoirs de la Societe geologique de France, 1854, Description des Bryozaires 

 fossiles de la formation Jiirassiqiie. 



^ See A. W. Waters, Bryozoa of the Bay of Naples, Ann. and Mag. Nat. Hist. 

 Tol. iii. 1879 ; also Journ. li. Microscop. Soc. vol. ii. xxiv. 



