I6t) REPOM— 1881. 



usually plain and non-celluliferous. Two species are described : T. exiguUf 

 Nich., and T. penniformis, Nich., both from the Hamilton group. 



In Clathropora the zoarium is a kind of membranous flattened ex- 

 pansion, with rounded or oval fenestras of considerable size. The cells are 

 on both sides, separated by a thin laminar axis. The fenestrae are 

 surrounded by a striped non-celluliferous margin. One species is de- 

 scribed — G. ititertexta, Nich. — from the Corniferous Limestone, but in 

 some respects it resembles P. coseiniformis, Nich., of which mention ha.s 

 already been made. 



In Heterodicta the zoarium forms a simple, flattened, unbranched, two- 

 edged frond, with sub-parallel sides. The cells are in two series ; the 

 central cells are perpendicular to the base, the lateral cells are oblique. 

 ' In the only species known — H. gigantea, Nich. — the cells of a few of the 

 median rows of the frond arc straight .... and, as I am only ac- 

 quainted with an exceedingly large species, I should, however, suspect 

 that Flnstra (JPtilodidya) lanceolata, Goldf., will very probably turn out 

 to be an example of this genus.' ' 



The material for a thorough revision of this genus is ' not easily 

 accessible. Many of the Bala series are beautiful casts only, and the Upper 

 Silurian species ai"e often bedded in blocks of the Dudley Limestone ; and I 

 think it very unwise to disturb the present nomenclature without suffi- 

 cient reason. 2 The MS. names of Mr. Robert Etheridge require con- 

 firmation, and the best way to do this would be to describe and figure 

 them. The new genera of Professor Nicholson may in the future em- 

 brace some few of the forms already described, but we can hardly super- 

 sede the clear definitions of Lonsdale's types as given by M'Coy. In the 

 Lower Ludlow rocks specimens of P. lanceolata, Goldf., often break up, 

 showing the concentrically wrinkled central axis. In the Girvan District 

 — Scotland — at least two distinct species of this genus may be found — 

 P. costellata, M'Coy, and P. dichotoma, Portl. 



1844. MTEIAPORID.S!, M'Coy. Family name only. 



This is the third family of M'Coy's very restricted classification of 

 Palaeozoic Polyzoa. It embraces the Retepora, Lamk. = to Elasmopora, 

 King. The family includes Glauconome, Goldfuss, restricted by Lons- 

 dale, and the genus Fenestella, Lonsdale. It is impossible to retain the 

 family name in the present Report. 



1849. Phyllopora, King. 



There are unquestionably present in both the American and British 

 Paleozoic rocks, species of Polyzoa having some of the inosculating 

 characters of Betepora cellulosa. These can neither be referred to 

 Fenestella nor Polypora. My objections to the term Retepora for these 

 have already been expressed. King, also, in his Permian Fossils, has ex- 

 pressed his dislike to this term, and he suggests another word to be used 

 instead — Phyllopora. I prefer this, especially as it has been consecrated 

 by two good workers — Salter and De Koninck. The earliest appear- 

 ance of the genus, so far as I am acquainted, is in the Lower Llandeilo^ 



' Geological Mag. 1875. 



2 Since writing the above I have been able to study, very carefullj-, the leading 

 types of Palfeozoic Ptilodictya. In a future paper on the Family Ptilodictid.iE I 

 shall be able to correct many inaccuracies of our ordinary nomenclature. 



^ School of Mines, iv. ~ in Catalogve of CamV, and Sil. I^ossih. 



