SEPTOPORA. 183 



Size. — A fragment containing six or seven cells measures 3 mm. in length and 

 is *5 mm. in width. 



Locality. — A single specimen from Lummaton is in my Collection. 



Remarks. — This species is only known to me by a single fragment, which does 

 not show any branching. In spite of its small dimensions it seemed impossible to 

 identify it with any of the accompanying Fenestellidse, both on account of its 

 general style and because there are no signs of any dissepiments, although a con- 

 siderable number of cells are seen. I was interested, therefore, to find an almost 

 identical fossil figured by Ulrich from the Lower Coal-measures of Illinois, especially 

 as his fossils showed the character of the branching and the striation of the 

 reverse side. There seems to be little doubt that these fossils are generically 

 identical, and hence, though some details are wanting for a complete description of 

 our species, I have no hesitation in giving it a specific name. 



Affinities. — This species, while coming very close to D. biserialls, Ulrich, 1 differs 

 in a few particulars. The apertures seem rather larger, less numerous, and less 

 marginal, and the keel is perhaps rather more prominent, and shows decided signs 

 of occasional slight prominences. 



I), marginalis, Young and Young, 2 is described as having a thin tuberculated 

 central keel, but it is also said to have two supplemental lateral keels. 



2. Genus. — Septopora, Front, 1859. 



Zoarium flabellate, with numerous primary branches, increasing by bifurcation 

 or interpolation, and so arranged that the smaller secondary branches unite with 

 those of adjacent stems. Reverse side usually finely striated, and bearing 

 scattered dimorphic pores ; celluliferous side with two rows of zooecia. Apertures 

 large. Devonian and Carboniferous. 



1. Septopora? sp. PI. XX, figs. 5, 5 a. 



Description. — Zoarium flabellate, consisting of an irregular network formed by 

 several primary branches radiating from a common centre or base, from the sides 

 of most of which sub-parallel secondary branches proceed at an angle of about 

 30°, generally decreasing in size according to their distance from the base, the 

 earlier secondary branches being nearly as large as the primary. Secondary 



1 Ibid., vol. viii, p. 637, pi. lxii, figs. 11— lie. 



2 1876, Young and Young, ' Proc. Nat. Hist. Soc. Glasgow,' vol. ii, pt. 2, p. 326, pi. iii, figs. 14 

 —21. 



