694 E. TvIRKrATRICK. 



network with tubercles at the nodes, and tabular floors. In 

 Rhaphidopora the tabulas have a central hole and radial 

 (? sutural) lines. In a former paper on Merlia I pointed 

 out that these resemblances might be merely homoeomor- 

 phous ; at the same time I hoped that Merlia might throw 

 light on the problem of the nature of Monticuli pora and 

 kindred organisms that have been placed by various authors 

 in widely different groups ; and I was rash enough to state 

 that there was now more evidence in favour of the theory 

 that some Monticulipores were sponges than in that of any 

 other theory concerning the nature of these fossils. 



After re-examining the large British Museum collection of 

 fossils, and sections of ]\Ionticulipora and allied forms, 

 especially the American series presented by Prof. Ray 

 Rassler, I doubt Avhether Merlia is going to throw light on 

 the problems concerning the nature of these organisms. It 

 would, indeed, be an astounding paradox to state that some 

 of the Palfeozoic so-called Tabulate corals (Nicholson) or 

 Polyzoa (Bassler) might prove to be the product of siliceous 

 sponges, but the theory here put forward concerning the 

 nature of Merlia is just such a paradox. At any rate the 

 fact must be taken into account that it is possible for a 

 siliceous sponge to make a tubular tabulate calcareous skeleton 

 with certain resemblances to some of the Palaeozoic Monti- 

 culiporas sensu lato. If Merlia had been found fossil, 

 Nicholson would certainly have classed it among the Tabulate 

 corals. Nickles and Bassler would, I think — but I write 

 subject to correction — have placed it among the Polyzoa, 

 possibly in a new sub-order, or in the Trepostomata, though 

 not in the family Monticuliporidte Nicholson (emend Ulrich) 

 (10), seeing that Merlia has no cystiphragms, mesopores, or 

 acanthopores. The zoologist who would propose to classify 

 a recent Merlia among the Foraminifera would naturally 

 place the fossil Merlia in that group. I myself at first 

 described the dried skeleton as that of a Pharetron sponge. 

 Certainly no paleontologist or zoologist would have regarded 

 such fossils or dried recent skeletons as products of siliceous 



