12 DEVONIAN FAUNA. 



rim in front. Basal lobes rather large, subtriangular. Glabella-furrows three 

 (including that which bounds the basal lobe), short, sufficiently clear except the 

 first. Neck-furrow deep. Neck-lobe arching, rather broad. Rim (in front of 

 glabella) rather broad, sigmoid in section. Fixed cheeks exceedingly narrow in 

 front, medianly convex at the eyes. Surface bearing numerous small scattered 

 tubercles. Free cheeks large, gently convex, subtriangular. Genal angles acute, 

 apparently prolonged into short spines. Eyes of medium size, elongate, bean- 

 shaped, rather elevated, situated centrally on the cheeks close to the glabella. 



Thorax large, of nine rather broad segments. Axis wide, elevated, semi- 

 cylindrical, bounded by deep axial furrows. Segments divided by a distinct central 

 groove on the limbs. 



Pygidium small, probably slightly broader than long, highly ornate, composed 

 of thirteen coalesced somites. Axis deeply convex, slightly flattened above, 

 nearly one-third the width of the pygidium at the proximal end, but diminishing 

 regularly and i^apidly, and terminating bluntly at a quarter the length of the 

 pygidium from the posterior margin, followed by an indistinct prolongation. 

 Rings of axis thirteen (of which eleven are distinct), narrow, elevated, each 

 bearing a row of about ten strong sharp tubercles. Limb with eight grooved 

 pleurae, each of which consists of a narrow raised rib, irregularly tubercled, 

 extending to, and apparently becoming wider at, the border, and of a lower 

 and shorter intermediate rib, similarly ornamented, and placed immediately 

 behind the major rib in the furrow. Border convex, broad, rather distinctly 

 defined by a linear depression, one-fifth the length of the tail behind, and becoming 

 slightly narrower laterally, the tuberculated ribs being visible across it. 



Size. — A specimen measures 18 mm. long by 8 mm. wide across the first, and 

 7 mm. wide across the last thoracic segment. A distorted glabella is 6 mm. long 

 by 3 mm. wide. A distorted pygidium is 7 mm. long by 11 mm. wide. 



Localities. — In the Barnstaple Athengeum is a complete but very much decayed 

 specimen from the shore near Fremingtou, and two beautifully preserved pygidia 

 labelled Pilton and Braunton Road ; and in the Porter Collection two pygidia and 

 a glabella from Pottington. All these specimens appear to have been collected 

 by Mr. Porter, and therefore probably all, except the first, may have come from one 

 locality. 



Bemarhs. — The complete specimen, occurring in light brown sandstone and 

 much decayed, is crushed obliquely, which perhaps gives it the appearance of being 

 more elongate than that it actually is, but even so it appears to be distinguishable 

 by the large relative size of the thorax and by its elongate form. It serves the 

 purpose of showing that the more perfectly preserved specimens of detached 

 pygidia and glabella belong to one species. 



The other specimens are in a much squeezed and twisted blue limestone ; and, 



