192 Mr. A. E. Verrill on the Classification of Polyps. 



existence of the three natural orders among Polyps, I refrained 

 from presenting this view in a paper published last year, in 

 order that I might make further investigations upon the sub- 

 ject before finally publishing it. 



Class CNIDARIA or POLYPI. 

 Order I. MADREPOllAUIA. 



Polyps simple or compound, with embryonic or rudimentary 

 basal or abactinal region, which has no special function, unless 

 for vegetative attachment while young. Actinal area well deve- 

 loped, form broadly expanded, having a tendency in the higher 

 groups to become narrowed towards the mouth. Tentacles 

 simple, conical. Dermal tissues and, usually, the radiating la- 

 mellse depositing solid coral ; the radiating plates, being between 

 the lamellse, are therefore ambulacral, and appear to originate 

 from the surfaces of the lamellae and the connective tissues ex- 

 tending across the ambulacral chambers and filling them from 

 below. Interambulacral spaces distinct. 



Suborder I. Stauracea [Madreporaria rugosa)^. 



Coral simple, or compound by budding ; chiefly epidermal and 

 endothecal; septa apparently in multiples of four, sometimes 

 wanting. Type embryonic, like a young Astrea or Fungia. 



Families: Stauridse, Cyathophyllidse, Cyathaxonidse, Cysti- 

 phyllidse. 



Suborder IT. Fungacea. 



Polyps either simple or compound by marginal or disk-bud- 

 ding, rarely by fissiparity. Tentacles numerous, in multiples 

 of six, imperfectly developed, scattered on the actinal surface, 

 usually short and lobe-like. Upper part of polyps scarcely ex- 

 sert. Coral broad and low, growth mostly centrifugal, tissue 



* This group is placed here with considerable hesitation, and principally 

 on account of the close resemblance in structure to the young of the suc- 

 ceeding and higher groups when they first begin to form a coral, which 

 then consists of a ring of epitheca or epidermal deposit, with a few, imper- 

 fect, rugose septa radiating from the centre. If the number four be a 

 constant feature of the arrangement of their septa, it is possible that they 

 may be entitled to rank as a separate order of Polyps. To this opinion 

 Prof. J. D. Dana inclines. Prof. Agassiz unites the group with Hydroid 

 Acalephs, on account of their resemblance in some features to the Tabulata. 

 It seems to me, however, that the absence of ti-ansverse plates in Cyathaxo- 

 nidse and Cystij)hyllid8e, and the perfection of the vertical septa in Stau- 

 ridaj, Cyathaxonida;, and some of the Cyathophyllida;, together with their 

 general structure, show them to be more closely allied to the Fungacea 

 and Astreacea, of which they may be considered embryonic types, while at 

 the same time the group is a synthetic one, having analogies witli nearly 

 all the higher groups of Polyps and also, in some respects, with Hydroids. 



