Prof. Nicholson on Classification of " Tabulate Corals" 103 



that the place of Chcctetes in the system must be very far 

 removed from that of Favosites. I am, nevertheless, satisfied 

 that Cha^tetes radians, Fischer, and the forms immediately 

 related to it, are genuine Actinozoa, though I am not able to 

 assign to them any certain place in this class. So far as one 

 can judge, they seem to have more affinity with the Alcy- 

 mmria than with any other group. 



The position of the numerous forms referred to, Monticuli- 

 pora, Fistulipoj-a, and other allied types, is, again, most un- 

 certain. Strong evidence has been brought forward to prove 

 that all these forms are really Polyzoa; but it certainly can- 

 not be said that this conjecture has, as yet, been sufficiently 

 proved. Some of these forms may very probably turn out to 

 be true Polyzoa ; but I am disposed to think that the majority 

 Avill prove to be referable to the Actinozoa. This seems to 

 be indicated as a general conclusion by their close resem- 

 blance, in many cases, to types of an undoubted Coelenterate 

 nature ; by the fact that their coralla are often composed of 

 two sets of corallites, pointing to a heteromorphic condition 

 of the zooids, such as is highly characteristic of many of the 

 Codenterata ; and lastly, by the fact that no forms possessing 

 their characteristic features in conjunction have as yet been 

 pointed out as existing either among recent or fossil Polyzoa. 

 Their alliances with Chmtetes proper are slight, and they 

 should be regarded as constituting a special group, to which 

 the name of Monticuliporidm may be given. 



XII. Labechiid.e. — This extraordinary group comprises 

 only the anomalous genus Lahechia, E. and H., at present 

 only known as a Silurian fossil. The skeleton in this genus 

 fornis a laminar or expanded mass, the under surface of which 

 is covered by an epitheca, while the upper surface shows an 

 apparently imperforate expanse, rising above which are close- 

 set tubercles. Microscopic sections show that these tubercles 

 are the projecting summits of short calcareous and solid, 

 but apparently primitively tubular, columns, separated from 

 one another by a loose vesicular tissue, formed by the anas- 

 tomoses of curved, calcareous lamellae. Dr Lindstrom has 

 strongly supported the view that Lahechia — originally placed 

 by Edwards and Haime among the Chmtetidce — is truly a 



