ON FOSSIL POLYZOA. 203 
no doubt but that other workers will find them if the sections are care- 
fully prepared. At the bases of some cells I have also detected circular 
openings, and as this would be the probable position of the funiculus of 
the polypide, this seems to me to be additional proof of the view I take. 
I have never been able to detect in any fossil specimens ordinary 
‘rosettenplaten ’ (communication pores, Hincks) other than the above, and 
Tam unable to furnish better details than the one already given; neither 
have I been able to detect in any of my numerous sections ‘connecting 
foramina ’ similar to, or in any way analogous with, the structure of the 
cell wall in Ptilodictya maculata, Ulrich, figured in the ‘ Am. Paleozoic 
Bryozoa,’ pl. VI. fig. 17. 
VIII. The tabule. I have already said that I have not been able to 
detect ‘tabule’ in any well-accredited species of Fossil Polyzoa. In 
Ptilodictya figured by me now, I have allowed a structure to appear which 
may be mistaken for tabule, but I think this would be an erroneous 
interpretation. I refer to the subject because Professor Nicholson 
describes tabule in Heterodictya, and Mr. Ulrich refers to ‘ diaphragms ’” 
in some of the ‘ robust cells’ of species of the genus. I have no desire to 
enter into controversy with other authors, but I hope that Professor 
Nicholson and also Mr. Ulrich will pardon me for making the following 
remarks on their labours. In ‘The Genus Monticulipora,’ p. 89, Professor 
Nicholson furnishes particulars of Heterodictya gigantea, Nich., and he 
gives figures of minute structures of the type. In the sections tabule 
are figured, and the walls are of a very peculiar character. This species, 
ce in fact many of the American Ptilodictya, differ from the type already 
escribed. 
Mr. Ulrich (op. cit. p. 162) accepts the genus Ptilodictya, Lonsdale, in 
which he includes Heterodictya, Nicholson (‘ Geo. Mag.’ 1875), but the 
characters which he gives as a diagnosis are not those of Lonsdale. I am 
obliged therefore to fall back very reluctantly upon my own labours,, 
which have now been carried on for a series of years; and accepting 
Ptilodictya Lonsdalei as the type, I found the following family for the: 
inclusion of a certain number of Paleozoic Polyzoa. 
Family Arcanororip”, Mihi. 
Zoarium woultiform. Zocecia tubular, or semitubular, orifice of cell 
obscured by vestibule ; true orifice of cell unknown. 
Genus Ptilodictya, Lonsd. Type P. Lonsdale’, Vine. 
», Arcanopora, Vine. »  Llustra? parallela, Phill. 
»  Glauconome, Goldf. ,, G. disticha, Goldf. 
Paitopictya, Lonsdale. 
Diagnosis of the genus already given. 
At present a revision of Ptilodictya seems to be impossible, but I may 
just indicate that the founding of two family names by Mr. Ulrich,. 
Ptilodictyonide and Stictoporide, appears to be warranted by the peculiar- 
character of the cell orifice, as well as by the cell arrangement. The 
only American species that comes nearest to P. Lonsdalei, Vine, is some- 
specimens of Rhinodictya granulosa, James, supplied to me by Mr. J. M.. 
Nickles. These, however, differ from the species R. granulosa, James,. 
