186 DEVONIAN FAUNA. 



viously described F. plebeia, and it appears to me that with that species these Pilton 

 fossils are identical. 



The only point in which Phillips's description does not agree with our fossils 

 is that he figures and describes the non-poriferous face as granular, whereas they 

 show it to be striated. A free specimen, however, from Ironpost has it tubercu- 

 lated, and though the fossil is obscure, it seems most likely that that feature is 

 due to mineral change acting perhaps on a finely granulated matrix, and may 

 have obliterated the original striation. 



2. Fenestella? umbrosa, n. sp. Plate XXII, figs. 16, 16 a; and Plate XXIII, 



figs. 2, 2 a, 3, 3 a. 



Description. — Zoarium large, convex, infundibuliform. Branches undulating, 

 stout, broader than the fenestrules, poriferous on the external face, which is 

 obliquely flattened, and appears to bear a thin sharp median keel. Non- 

 poriferous face with a few very strong longitudinal striae, of which the central 

 seems strongest, and perhaps forms an incipient keel. Cells two or three (or 

 occasionally even four) to a fenestrule, projecting (?) so as to cause indentations 

 on the sides of the branches. Fenestrules twelve to seventeen in the length of 

 10 mm., and about twenty-two in the width of 10 mm. Rate of branching about 

 one in seven. 



Size. — A doubtful crushed specimen is more than 80 mm. long. 



Localities. — In the Barnstaple Athenaeum is one specimen from Roborough ; 

 iu the Woodwardian Museum two from Barnstaple; in the Museum of Practical 

 Geology one from Croyde and one from the Pilton Beds; in the Porter Collection 

 six from Roborough, Poleshill, and Pilton ; and in my Collection one from 

 Croyde Rocks. 



B.emarlcs. — These specimens appear clearly to indicate a species distinct from 

 the common Pilton Fenestella plebeia both in general appearance and detail, and 

 distinguished from it by its stouter, more undulating branches, its smaller and 

 narrower fenestrules, its more rapid branching, its cup-like shape, and other 

 points. At the same time the imperfect state of our specimens, which are almost 

 all moulds or casts, makes it hard to say how much weight may be placed on 

 characters and measurements observable in them, and there are some inconsis- 

 tencies noticeable in them, rendering it not impossible that they include two 

 similar species, which cannot be separated without better material. Thus — 



(1) A specimen in the Woodwardian Museum, another in the Museum of 

 Practical Geology, and another in the Barnstaple Athenaeum show that the 



