174 DEVONIAN FAUNA. 



2. Germs. — Polypora, M'Coy, 1844. 



Zoarium differing from that of Fenestella by having more numerous rows of 

 cells, and by the absence of any median keel. Silurian to Trias. 



1. Polypora populata, n. sp. PI. XVIII, figs. 2 — 4 ; and PI. XIX, figs. 1, 1 a. 



? 1827. Gorgonia eieisteeia, Qoldfuss. Petref. Germ., p. 19, pi. vii, figs. 2 a, b. 

 ? 1841. Phillips. Pal. Foss., p. 20, pi. xi, fig. 30. 



1841. Ketepoea peisca, Phillips (not Qoldfuss). Ibid., p. 25, pi. xiii, fig. 37. 

 ? 1850. — hexagonum, F. A. Bomer. Beitr. Harzgeb., pt. 1, p. 6, pi. i, 



figs. 10 a, b. 



Description. — Zoarium large, spreading in an open cup or frond from a massive 

 base. Branches irregular (especially near base), frequently dividing, thick in the 

 centre so as to equal the fenestrules in width ; very deep, smooth and steeply 

 bevelled on the external or non-poriferous face, so as to become very narrow at 

 the top, where they are suddenly rounded ; rounded on the internal face, and 

 bearing four or five rows of alternating cells ; cells set obliquely so as to be 

 lozenge-shaped in the section taken parallel to the branches, and with free elevated 

 rounded distal ends, which give a nodulous appearance to the inner surface, and 

 which appear to have small mouths near their distal extremities. Dissepiments 

 short, indefinite, equal in width to the branches, but rather lower on the 

 external side, and appearing often to be more or less invaded by the cells. Cells 

 about six or seven to the length of a fenestrule. Fenestrules elongate, oval in the 

 centre, polygonal on the external face, similar in size throughout the zoarium, 

 numbering about four fenestrules to 10 mm. in length, and seven to 10 mm. 

 in width. 



Size. — A large but imperfect specimen measures about 55 mm. from the base 

 to the upper margin of the frond, and about 40 mm. across. 



Locality. — Lummaton. About seventeen specimens are in my Collection; two 

 very Hue examples, probably from the same place, in the Torquay Museum ; and 

 others in the Woodwardian. Phillips's figured specimen is in the British Museum. 



Remarks. — My friend Dr. Gregory regards this species as an aberrant form 

 of Polypora rather than a Phyllopora. It appears to be composed of true but 

 irregular branches, instead of being an homogeneous perforated network ; though 

 the short broad dissepiments, which are rather lower than the branches, seem to 

 be more or less occupied or invaded by cells, while the mode of the increase of the 



