FENESTELLA. 169 



2. Fenestella delta, n. sp. PI. XIX, fig. 2. 



Description. — Zoarium in parts flat, with slightly undulating, narrow branches, 

 united by stout, short, and low non-poriferous dissepiments. Branches strongly 

 obtusely keeled, with flat, oblique sides, bearing a row of cells with slightly 

 elevated round mouths, with thickened peristomes, at the rate of five or six cells 

 to a fenestrule. Fenestrules oblong or suboval, about 8 in 10 mm. of length, and 

 12 in 10 mm. of width. 



Size of fragment about 7 mm. wide. 



Locality. — Lummaton. Oue small specimen in my Collection. 



Remarks. — I have been able to identify only one single small fragment of 

 this species, and therefore can form no opinion as to the manner of growth of its 

 zoarium. It seems, however, to be a very distinct form, differing from the 

 common Lummaton Fenestella fanata by the triangular and strongly keeled shape 

 of its branches, and by having about six instead of three (or four) pores to a 

 fenestrule. I think, therefore, there is every reason for adding it to the list, 

 although it would have been more satisfactory to have had further evidence of its 

 character. From Pilton specimens of F. lacca, Ph., it is distinguished by its 

 stronger branches and dissepiments, its less angular fenestrules, and the smaller 

 number of its cells. 



This seems the nearest approach among our Devonian fossils to F. antiqua, 

 Goldfuss, sp.; 1 but it appears to be clearly distinguishable by its narrower 

 fenestrules and more numerous cells to a fenestrule. Goldfuss describes his 

 species as occurring both in the Devonian and the Zechstein, figuring a fragment, 

 natural size, from the former, and another, enlarged, from the latter, while his 

 description is too broad for specific distinction. Thus the only thing to be relied 

 on is the enlarged figure, which probably represents a distinct dolomitic species. 

 It would not, therefore, be safe to identify our fossil with F. antiqua, especially as 

 we have seen that under this name different authors refer to more than one of the 

 species which Goldfuss has described, and it remains to be decided which of them 

 has the prior claim to that name. 



Affinities. — F. regalis, Ulrich, 2 very closely approaches it, but seems to have 

 much larger fenestrules, more numerous cells, and closer mouths. 



F. funic ul a, 3 Ulrich, comes still nearer, but may, I think, be distinguished by its 

 laxer growth, longer fenestrules, more central apertures, and rather more strongly 

 corded keel ; while F. Cestriensis, Ulrich, 4 has smaller fenestrules, less undulating 



1 1826-33, Goldfuss, ' Petref. Germ.,' vol. i, p. 99, pi. xxxvi, figs. 3 a, b. 



2 1890, Ulrich, ' Geol. Surv. Illinois,' vol. viii, p. 538, pi. 1, figs. 1, 1 a ; and pi. liv, fig. 5. 



3 Ibid., p. 542, pi. li, fig. 6. 



* Ibid., p. 547, pi. li, figs. 5—5 b. 



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