ON FOSSIL POLYZOA. 171 



1825. Stomatopora, Bronn. 

 1821. Alecto, Lamx. 1820. Aulopora (pars.) Goldfuss. 



' Zoarium closely adnate thi^onghont, simple or irregularly branched ; 

 branches linear or ligulate ; cells disposed in a simple series or in more or 

 less regular transverse rows of from two to four.' ' 



A few types of this genus are present in the Palaeozoic rocks of this 

 country — in the Devonian of Bifel — and in America. 



James Hall, in his ' Pal.' of New York, vol. i., records the existence of 

 Alecto inflata in the Trenton Limestone. This is a very simple serial 

 species of a most remarkable type. From the same stratum lie records 

 another species, Aulopora araclmoidea, altogether different from the first 

 type. Except that Hall calls these species ' corals,' there are not in his 

 descriptions any characters that would prevent them being properly 

 placed with the Polyzoa. I have already alluded to this species, A. inflata, 

 Hall, when writing of Hippothoa. I now restore it to its proper place. 



1874. Alecto auloporides, Nich.^ 



„ frondosa = Aulopora frondosa, James. 

 1874. „ confusa, Nich. 



These seem to be true Stomatopora (Alecto of Busk), and their exist- 

 ence is recorded by Nicholson as appearing in the Lower Silurian or 

 Hudson River Group. One species, A. auloporides, as a branching form, 

 survives into the Niagara Limestone. In the Caradoc series of Fossils in 

 the School of Mines, a small specimen of Polyzoa is marked Heteropora, 

 allied to H. crassa.^ This is a very peculiar species, but in no way related 

 to Heteropora as now understood. The cells are short and tubular, 

 alternately placed on the sides of the branch, very similar to the figure given 

 by Nicholson. Having carefully examined the specimen, I therefore — 

 temporarily — place it as a variety, at least, of Stomatopora aulopondes, 

 Nich. 



I have, since the above was written, discovered no less than three 

 distinct STpecies ot Stomatopora in the Upper Silurian Shales of Shropshire. 

 One I have figured and described — S. dissimilis, Vine."* Of the others I have 

 not yet sufficient details to allow of description. I have also discovered 

 two species of Ascodictyon,^ full details of which will be published. In 

 King's Monograph of Permian Fossils, pi. 3, fig. 13, a figure is given of 

 — apparently — a badly preserved specimen of Stomatopora. It very much 

 resembles the species of Hall, but no cell-mouths are given. King names 

 it Aulopora [Stomatopora') Voigtiana, King. 



1839. Diastopora (Atdopora) cotisimilis, Lonsd. 

 A species of Polyzoa, named as above, is in the Ketley Collection at 

 the School of Mines. It is found in the Wenlock Limestone series, but 

 no locality is given. This is the Aulopora consimilis Lonsd. of the Silurian 

 System, pi. 15, fig. 7. I have found fragments in the washings of 

 Mr. Maw.^ Another specimen of the same species, from the Wenlock 

 Limestone, Dudley, encrusting a small coral, is in the cabinet of 



' Busk, Cyclostomata, p. 22. 



* Paper read at Brit. Assoc, Belfast ; printed. An, Mag. Nat. Hist., 1875. 

 ' Catalogue of Silwrian Fos., p. 44, case vii. ^. 

 ■• Geo. Soc. Pap. read June 22, 1881. 

 ' Nicholson, An. Mag. JVat. Hist., June, 1877. 



« In plate 1.5, Siluriam System, reproduced as pi. xli., Silnria, ed. 1859, marked 7, 

 Diastopora ? consimilis, probably a Bryozoon. 



