BEITISH PALJiOGENE BEYOZOA. 223 



There seems to be a similar evolutionary series in the Holothyriata, where the main 

 branch develops from the simple Cyclicoporince through the Lepralhm to the more 

 specialized Smittiidse; also in the Schizothyriata from the simple ScMzoporella or 

 Schismoporella to such a form as Adeonella pectinata. 



The division of both the Eeteporidee and Celleporidse into the schizostomatous and 

 holostomatous groups appears to be generally regarded as inevitable. The dis- 

 memberment of the Selenariidse is more likely to be criticized, but it is not a new idea. 

 It was first done by Prof. Smitt in 1873 [No. 3], and Mr. Hincks [No. 7, p. 125] has 

 given it the sanction of his high authority by the remark in describing Cupularia 

 imihellata, Defr., that " this form clearly belongs to the Steganoporellidan series and 

 must be transferred to it." 



The survival of the family Selenariidse seems to me to well illustrate the necessity 

 for a grouping of the families; so long as these have been allowed to remain in 

 independence, such an olla-podrida of species of different families agreeing only in 

 zoarial form has been able to hang together. The moment we introduce a more 

 scientific system, define suborders, and try to indicate the affinities of the families such 

 a group as the Selenariidse falls to pieces. 



These remarks are not intended as a formal defence of the classification. Its publi- 

 cation will be justified only if it is found to aid in bringing the Cheilostomata and 

 especially the fossil forms, into better order than they are in at present. 



Synopsis of the Classification followed. 

 Order CHEILOSTOMATA. 

 I. Suborder Stolon at a. 



Forms with simple tubular zooecia and terminal or subterminal apertures. 

 Family 1. Aeteid^. For diagnosis see Macgillivrayj No. 3, p. 195. 



2. EUCRATIID^E. „ „ „ p. 196. 



3. Chliboniii)^. „ „ „ p. 196. 



II. Suborder Cellularina. 

 A group of forms with simple zooecia and tufted phytoid zoaria^ and probaljly includino' repre- 

 sentatives of the three following suborders. 

 Family 4. Cellulariid^. For diagnosis see Macgillivray, No. 3, p. 199. 



5. BiCELLARIIDyE. „ „ „ p. 202. 



6. EpistomiidvE (Notamiidse) . „ Hincks, No. 2, p. 98. 



7. Catenicellidje. „ Macgillivray, No. 3, p. 197. 



8. BifaxariidvE. „ „ „ p. 199. 



III. Suborder Athyriata. 



Cheilostomata with the front wall uncalcified or incompletely calcified. 

 Family 9. FarciminariidjE. For diagnosis see Macgillivray, No. 3, p. 204. 

 10. Flustrid^. „ „ „ p. 203. 



